- Email: [email protected]
LARL) control of vasopressin release in the normal and streptozotocin diabetic rats
WS5-K-2-02 PHARYNGEAL/LARYNGEAL (PHRLILARL) CONTROL OF VASOPRESSIN RELEASE IN THE NORMAL AND STREPTOZOTOCIN DIABETIC RATS. T. Akaishi, S. Homma
Department of Physiology II, Niigata University School of Medicine, Niigata 951, Japan In human male, hypotonic diuresis is resulted only in the subjects who drink water (0.16 ml/kg b.wt.) sufficient to keep their oropharygeal/LARL mucosa moist continually over a 20 min period but not in those who drank the same volume of water within several seconds. On the other hand, the slow drinking of the same volume of hypertonic (0.30 M) saline produces hypertonic antidiuresis. Slow drinking of isotonic saline had no effect on urine excretion (Akaishi et al., Chemical Senses, 16:277-281, 1991). In order to know t h e n e u r o e n d o c r i n e basis in these results, the role of the pharynx and larynx in body water regulation was studied in urethane-anesthetized (1.2 g/kg, b.wt.) male rats by recording the electrical activities of supraoptic vasopressin (AVP) producing cells in the hypothalamus. Furthermore, the same study was also done in streptozotocin diabetic (STZ-DM) rat to know the pathophysiological state in the neuroendocrine control mechanism of AVP release. In the normal male rats, PHRL/LARL application of 0.15 ml/kg b.wt. water caused a decrease in the electrical activity of the AVP producing cell, whereas 0.30 M saline caused an increase in firing activity. Isotonic saline had no effect. Applications of 0.30 M saline to dorsal lingua had also no effect. Application of water containing 0.05 mM amiloride, a gustatory sodium antagonist, caused a decrease in firing activity. Hypertonic saline (0.30 M) containing 0.05 mM amiloride caused an insignificant change in their activity. Isotonic saline containing amiloride had no effect. In the DM rats received an intravenous injection of 60 mg/kg STZ 30-44 days before the experiment, water, 0.15 and 0.30 M saline caused similar but insignificant responses in the activity of the spontaneous discharge in the AVP cells examined. These data suggest that afferents from PHRL and/or LARL mucosa regulate the AVP release in association with the concentration of sodium chloride involved in the ingested solution, and that the gustatory reception of sodium is partially involved in this mechanism. In STZ-DM rats, the PHRL/LARL regulation of AVP release seemed to be relatively retained though it's defective.
WS5-K-2-03 HIGH SALT FOOD INTAKE DECREASES TISSUE NORADRENALIN CONTENTS AND INCREASES ORGAN WEIGHT IN DAHL-SALT SENSITIVE RATS Q. H. Chen, Y. Nishida, H. Morita and H. Hosomi Dept. of Physiol., Kagawa Medical School, Kagawa 761-07, Japan The purpose of the study was to determine the effects of 0.4 and 8% salt diet on tissue noradrenalin contents (NA) and organ weight (OW) in Dahl-salt-resistant (DSR) and Dahl-salt-sensitive rats (DSS). NA of 16 organs, i.e., cerebrum, brain stem, salivary gland, heart, aorta, stomach, jejunum, ileum, colon, liver, spleen, pancreas, kidney, adrenal gland, muscle, and bone, and OW of 6 organs, i.e., salivary gland, heart, stomach, spleen, kidney and adrenal gland were measured in DSR and DSS maintained on 0.4 or 8% salt diet for 0, 2, 4 and 6 weeks from 5 weeks after birth. In DSR with 0.4% salt diet, NA tended to increase from the 5 weeks old level and were maintained the level for the rest of the experiment in the most organs except the aorta, adrenal gland and muscle. OW of all organs except the cerebrum increased with increasing body weight (BW), but a ratio of each OW to BW decreased. These changes in NA and OW may be physiological phenomena due to aging. In DSR with 8% salt diet, NA did not show significant differences from 0.4% salt diet, but NA of the heart and kidney were lower than 0.4% salt diet. Thus, NA of the heart and kidney may be affected by 8% salt diet. A ratio of OW to BW increased in the kidney. In DSS with 0.4% salt diet, NA of the brain stem, heart, aorta, liver, adrenal gland and muscle decreased from the 5 weeks old level. NA of the rest of organs did not change with aging. Thus, DSS failed to show physiological changes in NA even with 0.4% salt diet. Changes in OW were similar to DSR. In DSS with 8% salt diet, NA of the heart, aorta, liver and adrenal gland, which moderately decreased in 0.4% salt diet, markedly decreased. NA of the brain stem in 8% salt diet decreased less than 0.4% salt diet. NA of the cerebrum did not change in 8% as well as 0.4% salt diet. NA of the other organs, which showed no change in 0.4% salt diet, moderately decreased in 8% salt diet. Ratios of OW of the heart, kidney and spleen to BW markedly increased. These changes may be a pathophysiological compensation to 8% salt diet. In conclusion, 0.4% salt diet failed to show physiological changes of NA in DSS and 8% salt diet decreased NA but the brain stem. 352
Department of Physiology II, Niigata University School of Medicine, Niigata 951, Japan In human male, hypotonic diuresis is resulted only in the subjects who drink water (0.16 ml/kg b.wt.) sufficient to keep their oropharygeal/LARL mucosa moist continually over a 20 min period but not in those who drank the same volume of water within several seconds. On the other hand, the slow drinking of the same volume of hypertonic (0.30 M) saline produces hypertonic antidiuresis. Slow drinking of isotonic saline had no effect on urine excretion (Akaishi et al., Chemical Senses, 16:277-281, 1991). In order to know t h e n e u r o e n d o c r i n e basis in these results, the role of the pharynx and larynx in body water regulation was studied in urethane-anesthetized (1.2 g/kg, b.wt.) male rats by recording the electrical activities of supraoptic vasopressin (AVP) producing cells in the hypothalamus. Furthermore, the same study was also done in streptozotocin diabetic (STZ-DM) rat to know the pathophysiological state in the neuroendocrine control mechanism of AVP release. In the normal male rats, PHRL/LARL application of 0.15 ml/kg b.wt. water caused a decrease in the electrical activity of the AVP producing cell, whereas 0.30 M saline caused an increase in firing activity. Isotonic saline had no effect. Applications of 0.30 M saline to dorsal lingua had also no effect. Application of water containing 0.05 mM amiloride, a gustatory sodium antagonist, caused a decrease in firing activity. Hypertonic saline (0.30 M) containing 0.05 mM amiloride caused an insignificant change in their activity. Isotonic saline containing amiloride had no effect. In the DM rats received an intravenous injection of 60 mg/kg STZ 30-44 days before the experiment, water, 0.15 and 0.30 M saline caused similar but insignificant responses in the activity of the spontaneous discharge in the AVP cells examined. These data suggest that afferents from PHRL and/or LARL mucosa regulate the AVP release in association with the concentration of sodium chloride involved in the ingested solution, and that the gustatory reception of sodium is partially involved in this mechanism. In STZ-DM rats, the PHRL/LARL regulation of AVP release seemed to be relatively retained though it's defective.
WS5-K-2-03 HIGH SALT FOOD INTAKE DECREASES TISSUE NORADRENALIN CONTENTS AND INCREASES ORGAN WEIGHT IN DAHL-SALT SENSITIVE RATS Q. H. Chen, Y. Nishida, H. Morita and H. Hosomi Dept. of Physiol., Kagawa Medical School, Kagawa 761-07, Japan The purpose of the study was to determine the effects of 0.4 and 8% salt diet on tissue noradrenalin contents (NA) and organ weight (OW) in Dahl-salt-resistant (DSR) and Dahl-salt-sensitive rats (DSS). NA of 16 organs, i.e., cerebrum, brain stem, salivary gland, heart, aorta, stomach, jejunum, ileum, colon, liver, spleen, pancreas, kidney, adrenal gland, muscle, and bone, and OW of 6 organs, i.e., salivary gland, heart, stomach, spleen, kidney and adrenal gland were measured in DSR and DSS maintained on 0.4 or 8% salt diet for 0, 2, 4 and 6 weeks from 5 weeks after birth. In DSR with 0.4% salt diet, NA tended to increase from the 5 weeks old level and were maintained the level for the rest of the experiment in the most organs except the aorta, adrenal gland and muscle. OW of all organs except the cerebrum increased with increasing body weight (BW), but a ratio of each OW to BW decreased. These changes in NA and OW may be physiological phenomena due to aging. In DSR with 8% salt diet, NA did not show significant differences from 0.4% salt diet, but NA of the heart and kidney were lower than 0.4% salt diet. Thus, NA of the heart and kidney may be affected by 8% salt diet. A ratio of OW to BW increased in the kidney. In DSS with 0.4% salt diet, NA of the brain stem, heart, aorta, liver, adrenal gland and muscle decreased from the 5 weeks old level. NA of the rest of organs did not change with aging. Thus, DSS failed to show physiological changes in NA even with 0.4% salt diet. Changes in OW were similar to DSR. In DSS with 8% salt diet, NA of the heart, aorta, liver and adrenal gland, which moderately decreased in 0.4% salt diet, markedly decreased. NA of the brain stem in 8% salt diet decreased less than 0.4% salt diet. NA of the cerebrum did not change in 8% as well as 0.4% salt diet. NA of the other organs, which showed no change in 0.4% salt diet, moderately decreased in 8% salt diet. Ratios of OW of the heart, kidney and spleen to BW markedly increased. These changes may be a pathophysiological compensation to 8% salt diet. In conclusion, 0.4% salt diet failed to show physiological changes of NA in DSS and 8% salt diet decreased NA but the brain stem. 352