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A comparative study of salivary secretion by parotid and mandibular glands of anaesthetized Capra hircus: Effect of pilocarpine
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Camp. Biochem. Physiol. Vol. 85C, No. 2, pp. 291-296, 1986 Printedin Great Britain
A COMPARATIVE STUDY OF SALIVARY SECRETION BY PAROTID AND MANDIBULAR GLANDS OF ANAESTHETIZED CAPRA HIRCUS: EFFECT OF PILOCARPINE C.
CASTELLANO, M.
MORENO, L. A.
and F. J. Departamento
Interfacultativo
de Fisiologia (Received
RAGGI, E. MARTINEZ DE VICTORIA MATAIX
Animal,
Universidad
11 February
de Granada,
Granada,
Spain
1986)
Abstract-l. A study was made of basal secretion and the effect of the infusion of pylocarpine on the flow and composition of saliva in the parotid and mandibular glands of the anaesthetized lactating goat. 2. In the parotid gland there was a basal flow (1.6 k 0.29 pl/min) which was not present in the
mandibular gland. 3. There is a statistically significant dose-effect relationship between pilocarpine and salivary flow in both glands. 4. Saliva1 composition and its variation with respect to the flow of saliva did not conform the two glands to an exclusive monogastric or ruminant model.
INTRODUCTION
There have been numerous studies carried out on salivary secretion in adult ruminants. Nevertheless, for ruminants, as for other mammal species, there has been very little research into lactating animals or into those at different stages of development; there is little information available on the evolution of salivary secretion from birth to maturity. The object of this study was to establish a comparison between the behaviour of the parotid and mandibular glands in the anaesthetized kid goat, in the resting state and in response to a parasympathomimetic agent; and to establish the relationships between the flow of saliva and the concentration of different ions in it. MATERIALS
AND METHODS
We used 26 kid goats of the “granadina” breed, weighing between 2.5 and 4.0 kg, l&20 days old, anaesthetized with ethylurethane at 30% (w/v). After tracheotomy and routine draining of the urinary bladder, the main excretory duct of a parotid gland and of a mandibular gland was cannulated through a polyvinyl tube. The right femoral vein and artery were similarly cannulated, the latter in order to control arterial pressure and the former to carry out the infusion of pilocarpine. Temperature was maintained constant throughout the experiment (39 + 1°C). Salivary flow was determined through a dropcounter, the density of the saliva being considered equal to one. Pressure was measured by means of a “Statham P.230b” transducer connected to a “Physiograph E & M” polygraph (NARCO BIDSYSTEM). The infusion of pilocarpine was through a peristaltic pump, connected to the femoral vein. The pilocarpine used was in the form of chlorhydrate (MERCK) and at dosages of between 1.0 and 12.4 pg/min/ kg wt. Analylic
techniques
The concentration of Na+ and K+ was determined atomic absorption spectrophotometry (PYE UNICAM
by SP
90A).
291
to either of
The concentration of chloride was obtained by potentiometric measurement with NO,Ag using a system of titration in the end point (ETS 822 RADIOMETER A/S Copenhagen). The concentration of inorganic phosphorus was colorimetrically determined using the Fiske-Subbarow method (1925). Statistical evaluation was performed with linear regression analysis and Student’s t-test. Values for P of less than 0.05 were considered significant. Mean values are expressed as mean + SE. RESULTS
In the absence of known external stimuli and with inervation and irrigation intact, we measured a basal saliva flow in the parotid gland of 1.6 f 0.29pi/ min (N = 8) which remained effectively constant, throughout the experimental period. This saliva had a Na+ content of 168.3 + 28.65mEq/l (N = 6), a K+ content of 22.0 f 4.34mEq/l (N = 6) and Clcontent of 51.8 f 15.65 mEq/l. In the mandibular gland, only five animals out of a total of 26 produced a basal flow under equal experimental conditions, with an average value of 0.9 + 0.25 pl/min that, in every case, disappeared with t&e. The administration of pilocarpine at all the dosages tested gave rise, in every case, to an increase in salivary flow in both glands, with a good dose-effect relationship (P < 0.001) (Fig. 1). In the parotid gland, the concentrations of Na+ were greater than those found in the mandibular gland, with values measured between 2-224 and 0.19-37.5 mEq/l, respectively. The content of this ion in the parotid gland increased with the flow, there being a statistically significant logarithmic correlation (P < 0.05). In the mandibular gland, on the contrary, the concentration of Na+ was independent of salivary flow (Fig. 2). Figure 3 shows that the concentrations of Cl- both in the mandibular gland and in the parotid gland
C.
292
4 -4
CASTELUNO
I
al.
should not discount the negative action that the extreme viscosity of the saliva from this gland must have on salivary flow.
Parotid hkmdibular
4
et
I
8 ckbse(pJ/kg/min)
I
12
Fig. 1. Linear correlation between dose and flow of saliva in the parotid and mandibular glands. were of similar values, of between 10 and 60 mEq/l,
there being no correlation between the flow and the anion concentration. The concentration of K+ reached similar levels in the two glands (2.5-40mEq/l in the parotid gland and 6.5-33mEq/l in the m~dibular gland). However, while the former concentration was independent of flow, in the mandibular gland there was a reduction in concentration as flow increased (P < 0.001) (Fig. 4). Concentration of inorganic phosphorus was measured at between 10 and 70 mM/l in the parotid gland, diminishing as flow increased (P < 0.05). Concentration was much lower in the mandibular gland, between 0.01 and 0.8 mM/I, independent of the flow of saliva (Fig. 5). DISCUSSION
Busal J?OW
In the case of the parotid gland, basal flow was difficult to compare with results of other researchers, due to the age of the animals we used. Nevertheless, it was less than that described by Kay (1960b) for animals five weeks old. This lesser flow could be due partly to the different anaesthetic used in each case, and to the increase in salivary flow, observed in interdigestive periods, with respect to the age of the animal (Kay, 1960b). With respect to the composition of electrolytes, we observed that the concentration of Na+ was equal or slightly superior to the plasma value (Compton et al., 1980) and similar to those described for the saliva of this species (Kay, 1960b) and of the adult sheep (Coats and Wright, 1957; Kay, 1960a). The concentration of K+ was again similar to that described by Kay (1960b) for this species, but slightly higher than that of the sheep (Coats and Wright, 1957; Kay, 1960a; Beal, 1979). On the other hand, the concentration of chloride was greater than that described in adult sheep (Isac, 1984), which could be due to the substitution of salivary chloride by phosphates, which occurs with age (Dancis et al., 1957). The flow observed in the mandibular gland in these conditions could be more an effect of cannulation than a secretion from genuine repose, though we
The results described for the parotid gland of lactating kid goats coincide with those obtained for this gland from adult goats (Isac, personal communication) and with those we ourselves have described for the parotid gland of the adult rabbit; however, they were contrary to those obtained from the mandibular gland of the latter species (Moreno et al., 1981). These similar correlations between the dose of pilocarpine and salivary flow in the two glands were produced in animals between 10 and 20 days old, and will not necessarily be seen in adult animals since, according to various authors on rats (Jawby and Leeson, 1959; Schneyer and Schneyer, 1961; Schneyer and Hall, 1968) and to Kay (1960b) on this same species, there is a certain immaturity of the salivary glands at birth with has repercussions on the level of its secretion and on the response to secretagoges agents. In the case of the ruminant, due to the important functional and feeding changes with respect to the pre-ruminant, it is possible that the response of the two glands to secretagogues agents may not be similar. The relationship found for Na+ in the parotid gland in kid goats was comparable to that described for the same gland in the rabbit (Mangos et a/., 1973; Martinez de Victoria, 1977) and in the rat (Schneyer and HaIl, 1965). Therefore it seems that Na+ is reabsorbed into the duct system of the parotid gland, which would result in an increase in concentration as the flow increases. In the case of the mandibular gland, although our results agree with those described by other authors (Schneyer and Schneyer, 1960; Young and Schiigel, 1966; Kakudo et al., 1970) in that the concentration was less than that found in parotid saliva, they differ in that the concentration was independent of the flow, which was attributed to the lack of glandular maturity due to the age of the animals used, although Schneyer et al. (1972) indicated that, in rats, there were no significant changes in the salivary content of Na’ with age. The measured values of the chloride anion in the parotid and mandibular glands in lactating kid goats were slightly greater than’ those described for the parotid gland of the adult sheep (Compton et al., 1980), these authors finding no clear relation between flow and concentration. Kay (196Oa), studying nonanaesthetized sheep, observed an increase in concentration of the anion as flow increased, which was similar to that described for monogastric animals (Yoshimura et al., 1959; Mangos et al., 1973; Martinez de Victoria, 1977; Compton et al., 1981; Young et al., 1981). Finally, Coats and Wright (1957), studying anaesthetized sheep, discovered a negative correlation between flow and chloride concentration, with the ion diminishing as flow increases; while Beal (1979), studying the sheep parotid, found no relation, either, between flow and chloride concentration after the administration of acetylcholine. Our results correspond to those of this author for adult sheep, in spite of the fact that one would have
Pilocarpine and salivary secretion in goat
293
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. .
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.
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Fig. 4. Relationship between flow of saliva and concentration of potassium in the parotid and mandibular glands. expected a similar behaviour to that described for monogastric animals, given the age of the animals we used. The greater values of chloride concentration obtained by us, with respect to adults animals (Coats and Wright, 1957; Kay, 1960a; Beal, 1979; Compton et al., 1980), may be explained with reference to the descriptions by Dancis et al. in 1957 of the interchanging of chloride with phosphate. The results describing the concentration of KC agree with those obtained for the parotid gland of the rabbit (Mangos et al., 1973) and of the rat (Schneyer and Hall, 1965). In the manidublar gland, they coincide with those reported by Mangos et al. (1973) in the same rabbit gland, but differ from the data for the rat mandibular (Schneyer and Schneyer, 1960; Young and Schiigel, 1966; Kakudo et al., 1970) where the concentrations, apart from being higher, are also independent of the flow. From these patterns, it may be deduced that potassium is secreted at the level of the glandular ducts (Young et al., 1967; Kaladelfos, 1971; Young et al., 1981). This secretion could vary in magnitude from one gland to another, which, combined with the possible direct effect of pilocarpine on the secretion of this ion (Schneyer et al., 1972), could explain the distinct patterns of the two glands.
The greater concentration of inorganic phosphorus found in parotid saliva with respect to mandibular seems logical, since it is the parotid which is responsible in adult animals, for secreting large quantities of saliva, as a buffer effect. The reaction of the inorganic phosphorus in the parotid gland in kid goats, similar to that which occurs in adult goats (Isac, 1984), may well be explained as a dilution effect, agreeing with Compton et al. (1980) in the sense that the phosphorus only enters at the level of the primary saliva, although, according to the same authors, it could be due secondarily to a ductal reabsorption of water. Salivary composition and its modification with flow, at this stage of the development of the kid goat, do not conform, in either of the two glands, to one exclusive model-monogastric or ruminant-in spite of the fact that a priori one would expect responses typical of a monogastric animal. REFERENCES
Beal A. M. (1979) Parotid salivary flow and composition during infusion of acetylcholine and atropine into the carotid artery of conscious sodium replete sheep. Q. J. exp. Physiol. 64, 89-107.
Pilocarpine and salivary secretion in goat
?
r
295
Mandibular
. . l
..
.
:
.
. .
.
.
l .
I 0
I
40
I
60 Flow f+ Anin)
l
I 120
f
I 160
Fig. 5. Relationship between flow of saliva and concentration of inorganic phosphorus in the parotid and mandibular glands, Coats D. A. and Wright R. D. (1957) Secretion by the parotid gland of the sheep: the relationship between salivary flow and composition. 1. Physiol. 135, 611622. Compton J. S., Nelson R., Wright R. D. and Young J. A. (1980) A micropuncture investigation of electrolyte transport in the parotid glands of sodium-repleted and sodiumdepleted sheep. J. Physiol. 309, 429-446. Compton J. S., Martinez J. R., Marina Martinez A. and Young J. A. (1981) Fluid and electrolyte secretion from the isolated, perfused submandibular and sublingual glands of the rat. Archs oral Biol. 26, 555-561. Dancis J., Grobow G. and Boyer A. (1957) The chloride concentration of saliva and sureat in infancy. J. Pediat. 50, 459462.
Fiske C. H. and Subbarow Y. (1925) The calorimetric determination of phosphorus. J. biol. Chem. 66, 375400. Isac M. D. (1984) Secretion parotidea en la cabra: influencias vegetativas y paratiroideas. Tesis Doctoral, Universidad de Granada. Jacoby F. and Leeson C. R. (1959) The postnatal development of the rat submaxillary glands. J. Anat. 93,201-216. Kakudo Y., Yoshida Y. and Mukai J. (1970) Studies on a dynamic cation transport in the rat submaxillary glands by carbonic anhydrase inhibitors. J. Osaka dent. Univ. 4, 95-l 12.
Kaladelfos G. (1971) Fluid and electrolyte excretion in primary and final saliva of the submaxillary and sublingual glands of the cat. Honors Thesis, University of Sydney. Kay R. N. B. (1960a) The rate of flow and composition of
various salivary secretions in sheep and calves. J. Physiol. 150, 515-537. Kay R. N. B. (1960b) The development of parotid salivary secretion in young goats. J. Physiol. 150, 538-545. Mangos J. A., McSherry N. R., Irwin K. and Hong R. (1973) Handling of water and electrolytes by rabbit parotid and submaxillary glands. Am. J. Physiol. 225, 450455.
Martinez de Victoria E. (1977) Influencias simpaticas sobre la secretion de saliva por la glandula parotida en conejos anestesiados. Tesis Doctoral, Universidad de Granada. Moreno M., Martinez de Victoria E. and Lopez M. A. (1981) Influencias de la pilocarpina sobre el flujo de saliva en las glandulas parotida y mandibular de1 conejo. Ars Pharmacetitica XXII, 217-223. Schneyer C. A. and Hall H. D. (1965) Comparison of rat salivas evoked by auriculotemporal and pilocarpine stimulation. Am. J. Physiol. 209, 484488. Schneyer C. A. and Hall H. D. (1968) Time course and autonomic regulation of development of secretory function of rat parotid. Am. J. Physiol. 214, 808-813. Schneyer C. A. and Schneyer L. H. (1960) Electrolyte levels of rat salivary secretions in relation to fluid-flow rate. Am. J. Physiol. 199, 55-58. Schneyer C. A. and Schneyer L. H. (1961) Secretion by salivary glands deficient in acini. Am. J. Physiol. 201, 939-942.
Schneyer L. H., Young J. A. and Schneyer C. A. (1972) Salivary secretion of electrolytes. Physiol. Reo. 52, 72G 777.
296
C. CASTELLANO et al.
Yoshimura H., Iwasaki H., Nishikawa T. and Matsumoto S. (1959) Role of carbonic anhydrase in the bicarbonate excretion from salivary glands and mechanism of ionic excretion. Jap. J. Physiol. 9, 106123. Young J. A. and Schiigel E. (1966) Micropuncture investigation of sodium and potassium excretion in rat submaxillary saliva. Arch. ges. Physiol. 291, 85-98. Young J. A., Case R. M., Conigrave A. D., Novak I. and Thompson C. H. (1981) Secretory
processes in the perfused rabbit mandibular gland. In Saliva and Salivation, 1st edn (Edited by Zelles T.), Vol. 26, pp. 3546. Pergamon Press, Budapest. Young J. A., Framter E., Schiigel E. and Hamann K. F. (1967) A microperfusion investigation of sodium resorption and potass:um secretion by the main excretory duct of the rat submaxillary gland. Arch. ges. Physiol. 295, 157-172.
Camp. Biochem. Physiol. Vol. 85C, No. 2, pp. 291-296, 1986 Printedin Great Britain
A COMPARATIVE STUDY OF SALIVARY SECRETION BY PAROTID AND MANDIBULAR GLANDS OF ANAESTHETIZED CAPRA HIRCUS: EFFECT OF PILOCARPINE C.
CASTELLANO, M.
MORENO, L. A.
and F. J. Departamento
Interfacultativo
de Fisiologia (Received
RAGGI, E. MARTINEZ DE VICTORIA MATAIX
Animal,
Universidad
11 February
de Granada,
Granada,
Spain
1986)
Abstract-l. A study was made of basal secretion and the effect of the infusion of pylocarpine on the flow and composition of saliva in the parotid and mandibular glands of the anaesthetized lactating goat. 2. In the parotid gland there was a basal flow (1.6 k 0.29 pl/min) which was not present in the
mandibular gland. 3. There is a statistically significant dose-effect relationship between pilocarpine and salivary flow in both glands. 4. Saliva1 composition and its variation with respect to the flow of saliva did not conform the two glands to an exclusive monogastric or ruminant model.
INTRODUCTION
There have been numerous studies carried out on salivary secretion in adult ruminants. Nevertheless, for ruminants, as for other mammal species, there has been very little research into lactating animals or into those at different stages of development; there is little information available on the evolution of salivary secretion from birth to maturity. The object of this study was to establish a comparison between the behaviour of the parotid and mandibular glands in the anaesthetized kid goat, in the resting state and in response to a parasympathomimetic agent; and to establish the relationships between the flow of saliva and the concentration of different ions in it. MATERIALS
AND METHODS
We used 26 kid goats of the “granadina” breed, weighing between 2.5 and 4.0 kg, l&20 days old, anaesthetized with ethylurethane at 30% (w/v). After tracheotomy and routine draining of the urinary bladder, the main excretory duct of a parotid gland and of a mandibular gland was cannulated through a polyvinyl tube. The right femoral vein and artery were similarly cannulated, the latter in order to control arterial pressure and the former to carry out the infusion of pilocarpine. Temperature was maintained constant throughout the experiment (39 + 1°C). Salivary flow was determined through a dropcounter, the density of the saliva being considered equal to one. Pressure was measured by means of a “Statham P.230b” transducer connected to a “Physiograph E & M” polygraph (NARCO BIDSYSTEM). The infusion of pilocarpine was through a peristaltic pump, connected to the femoral vein. The pilocarpine used was in the form of chlorhydrate (MERCK) and at dosages of between 1.0 and 12.4 pg/min/ kg wt. Analylic
techniques
The concentration of Na+ and K+ was determined atomic absorption spectrophotometry (PYE UNICAM
by SP
90A).
291
to either of
The concentration of chloride was obtained by potentiometric measurement with NO,Ag using a system of titration in the end point (ETS 822 RADIOMETER A/S Copenhagen). The concentration of inorganic phosphorus was colorimetrically determined using the Fiske-Subbarow method (1925). Statistical evaluation was performed with linear regression analysis and Student’s t-test. Values for P of less than 0.05 were considered significant. Mean values are expressed as mean + SE. RESULTS
In the absence of known external stimuli and with inervation and irrigation intact, we measured a basal saliva flow in the parotid gland of 1.6 f 0.29pi/ min (N = 8) which remained effectively constant, throughout the experimental period. This saliva had a Na+ content of 168.3 + 28.65mEq/l (N = 6), a K+ content of 22.0 f 4.34mEq/l (N = 6) and Clcontent of 51.8 f 15.65 mEq/l. In the mandibular gland, only five animals out of a total of 26 produced a basal flow under equal experimental conditions, with an average value of 0.9 + 0.25 pl/min that, in every case, disappeared with t&e. The administration of pilocarpine at all the dosages tested gave rise, in every case, to an increase in salivary flow in both glands, with a good dose-effect relationship (P < 0.001) (Fig. 1). In the parotid gland, the concentrations of Na+ were greater than those found in the mandibular gland, with values measured between 2-224 and 0.19-37.5 mEq/l, respectively. The content of this ion in the parotid gland increased with the flow, there being a statistically significant logarithmic correlation (P < 0.05). In the mandibular gland, on the contrary, the concentration of Na+ was independent of salivary flow (Fig. 2). Figure 3 shows that the concentrations of Cl- both in the mandibular gland and in the parotid gland
C.
292
4 -4
CASTELUNO
I
al.
should not discount the negative action that the extreme viscosity of the saliva from this gland must have on salivary flow.
Parotid hkmdibular
4
et
I
8 ckbse(pJ/kg/min)
I
12
Fig. 1. Linear correlation between dose and flow of saliva in the parotid and mandibular glands. were of similar values, of between 10 and 60 mEq/l,
there being no correlation between the flow and the anion concentration. The concentration of K+ reached similar levels in the two glands (2.5-40mEq/l in the parotid gland and 6.5-33mEq/l in the m~dibular gland). However, while the former concentration was independent of flow, in the mandibular gland there was a reduction in concentration as flow increased (P < 0.001) (Fig. 4). Concentration of inorganic phosphorus was measured at between 10 and 70 mM/l in the parotid gland, diminishing as flow increased (P < 0.05). Concentration was much lower in the mandibular gland, between 0.01 and 0.8 mM/I, independent of the flow of saliva (Fig. 5). DISCUSSION
Busal J?OW
In the case of the parotid gland, basal flow was difficult to compare with results of other researchers, due to the age of the animals we used. Nevertheless, it was less than that described by Kay (1960b) for animals five weeks old. This lesser flow could be due partly to the different anaesthetic used in each case, and to the increase in salivary flow, observed in interdigestive periods, with respect to the age of the animal (Kay, 1960b). With respect to the composition of electrolytes, we observed that the concentration of Na+ was equal or slightly superior to the plasma value (Compton et al., 1980) and similar to those described for the saliva of this species (Kay, 1960b) and of the adult sheep (Coats and Wright, 1957; Kay, 1960a). The concentration of K+ was again similar to that described by Kay (1960b) for this species, but slightly higher than that of the sheep (Coats and Wright, 1957; Kay, 1960a; Beal, 1979). On the other hand, the concentration of chloride was greater than that described in adult sheep (Isac, 1984), which could be due to the substitution of salivary chloride by phosphates, which occurs with age (Dancis et al., 1957). The flow observed in the mandibular gland in these conditions could be more an effect of cannulation than a secretion from genuine repose, though we
The results described for the parotid gland of lactating kid goats coincide with those obtained for this gland from adult goats (Isac, personal communication) and with those we ourselves have described for the parotid gland of the adult rabbit; however, they were contrary to those obtained from the mandibular gland of the latter species (Moreno et al., 1981). These similar correlations between the dose of pilocarpine and salivary flow in the two glands were produced in animals between 10 and 20 days old, and will not necessarily be seen in adult animals since, according to various authors on rats (Jawby and Leeson, 1959; Schneyer and Schneyer, 1961; Schneyer and Hall, 1968) and to Kay (1960b) on this same species, there is a certain immaturity of the salivary glands at birth with has repercussions on the level of its secretion and on the response to secretagoges agents. In the case of the ruminant, due to the important functional and feeding changes with respect to the pre-ruminant, it is possible that the response of the two glands to secretagogues agents may not be similar. The relationship found for Na+ in the parotid gland in kid goats was comparable to that described for the same gland in the rabbit (Mangos et a/., 1973; Martinez de Victoria, 1977) and in the rat (Schneyer and HaIl, 1965). Therefore it seems that Na+ is reabsorbed into the duct system of the parotid gland, which would result in an increase in concentration as the flow increases. In the case of the mandibular gland, although our results agree with those described by other authors (Schneyer and Schneyer, 1960; Young and Schiigel, 1966; Kakudo et al., 1970) in that the concentration was less than that found in parotid saliva, they differ in that the concentration was independent of the flow, which was attributed to the lack of glandular maturity due to the age of the animals used, although Schneyer et al. (1972) indicated that, in rats, there were no significant changes in the salivary content of Na’ with age. The measured values of the chloride anion in the parotid and mandibular glands in lactating kid goats were slightly greater than’ those described for the parotid gland of the adult sheep (Compton et al., 1980), these authors finding no clear relation between flow and concentration. Kay (196Oa), studying nonanaesthetized sheep, observed an increase in concentration of the anion as flow increased, which was similar to that described for monogastric animals (Yoshimura et al., 1959; Mangos et al., 1973; Martinez de Victoria, 1977; Compton et al., 1981; Young et al., 1981). Finally, Coats and Wright (1957), studying anaesthetized sheep, discovered a negative correlation between flow and chloride concentration, with the ion diminishing as flow increases; while Beal (1979), studying the sheep parotid, found no relation, either, between flow and chloride concentration after the administration of acetylcholine. Our results correspond to those of this author for adult sheep, in spite of the fact that one would have
Pilocarpine and salivary secretion in goat
293
. . .
l
l
. l
.
l
l
. .
. .
. .
l * l l . .
.
0.
. l*
l l l l
294
C. CASTELLANO et al. Parotid
. .
r
Mandibular
-
Go
G 5
.*. Ii.:::*&ii+_.. .. . .. y * 33.95 - 4.53 In x
.
r = 0.6289
P e 0.001
.*q*
Y
‘co20
G
,...; _
P
e
g ‘:
Y
.s=,
l
.
.*
l
. .
IO
.
l
. .
:
. .
.
s
t L
I
0
I
I a0
40
I
I
120
160
Flow (@IminI
Fig. 4. Relationship between flow of saliva and concentration of potassium in the parotid and mandibular glands. expected a similar behaviour to that described for monogastric animals, given the age of the animals we used. The greater values of chloride concentration obtained by us, with respect to adults animals (Coats and Wright, 1957; Kay, 1960a; Beal, 1979; Compton et al., 1980), may be explained with reference to the descriptions by Dancis et al. in 1957 of the interchanging of chloride with phosphate. The results describing the concentration of KC agree with those obtained for the parotid gland of the rabbit (Mangos et al., 1973) and of the rat (Schneyer and Hall, 1965). In the manidublar gland, they coincide with those reported by Mangos et al. (1973) in the same rabbit gland, but differ from the data for the rat mandibular (Schneyer and Schneyer, 1960; Young and Schiigel, 1966; Kakudo et al., 1970) where the concentrations, apart from being higher, are also independent of the flow. From these patterns, it may be deduced that potassium is secreted at the level of the glandular ducts (Young et al., 1967; Kaladelfos, 1971; Young et al., 1981). This secretion could vary in magnitude from one gland to another, which, combined with the possible direct effect of pilocarpine on the secretion of this ion (Schneyer et al., 1972), could explain the distinct patterns of the two glands.
The greater concentration of inorganic phosphorus found in parotid saliva with respect to mandibular seems logical, since it is the parotid which is responsible in adult animals, for secreting large quantities of saliva, as a buffer effect. The reaction of the inorganic phosphorus in the parotid gland in kid goats, similar to that which occurs in adult goats (Isac, 1984), may well be explained as a dilution effect, agreeing with Compton et al. (1980) in the sense that the phosphorus only enters at the level of the primary saliva, although, according to the same authors, it could be due secondarily to a ductal reabsorption of water. Salivary composition and its modification with flow, at this stage of the development of the kid goat, do not conform, in either of the two glands, to one exclusive model-monogastric or ruminant-in spite of the fact that a priori one would expect responses typical of a monogastric animal. REFERENCES
Beal A. M. (1979) Parotid salivary flow and composition during infusion of acetylcholine and atropine into the carotid artery of conscious sodium replete sheep. Q. J. exp. Physiol. 64, 89-107.
Pilocarpine and salivary secretion in goat
?
r
295
Mandibular
. . l
..
.
:
.
. .
.
.
l .
I 0
I
40
I
60 Flow f+ Anin)
l
I 120
f
I 160
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