The respiratory properties of the blood of the bladdernose seal (Cystophora cristata)

Respiration Physiology (1969) 7, l-6; North-Holland Publishing Company, Amsterdam

TJ3E RESPIRATORY

PROPERTIES

THE BLADDERNOSE

OF THE BLOOD

OF

SEAL (Cystophora cristata)

GUNNAR CLAUSEN AND AMUNDERSLAND Institute of Physiology, University of Bergen, Norway

Abstract. The blood of about three months old Cystophora had an OS.capacity of 36 vol %. RBC was normal, 4.8 x 106/mms, but Hct and Hb content were very high, 63 % and 26.4 g /lOOml. When calculating the MCV as Hct/RBC x 10 and from the Price-Jones curve the mean values were 131 and 135 ps. The Cystophora red blood cell was 60% larger and had a 30% higher MCHC than that of humans. The TSOwas 24 mm Hg and the mean Bohr effect factor (A log Tsa/ApH) was -0.66, i.e. somewhat higher than in previously investigated mammalian divers. Relatively high Haldane effect, 8.4 vol % CO%,and buffering capacity (A[HCO;I/ApH), -36 meq/L, were found in the blood. It is generally concluded that the investigated characteristics of Cystophora blood differ from those of human blood in accordance with its higher Hb content. Buffering capacity COZ dissociation HbOz dissociation

In a sea lion (Eumethopsis

0s capacity T50 Red

cell volume

stelleri) an exceptionally high O2 capacity per volume red cells (0.68 cc O&c cells) was found by FL~RKIN and REDFIELD (1931). The Hct of the single sample available was only 29. IRVING et al. (1935) found 0.61 cc O&c cells in the blood from harbour seals (Phoca vitulina). They found a RBC of 6 x 106/mm3 and a normal Hct, and concluded that the red cells are smaller than those of human blood. IRVING et al. where not satisfied that their Hb data giving 1.78 cc 0,/g I-lb were correct. There is no doubt that seal blood does have exceptionally high O2 capacities. SCHOLANDER (1940) has shown this in the grey seal (Helichoerus grypus) and the present species. It is not clear, however, whether this high 0, capacity is associated with a high MCHC, a high Hct or with a special feature of seal Hb itself. Both the I-IbOz and the CO1 dissociation have been studied, but pH was not determined in any of the above mentioned papers. In the Cystophora the gas equilibrium of the blood was evaluated from alveolar gas concentrations and arterial gas contents during prolonged submersions (SCHOLANDER, 1940). These results, however, were influenced by progressive acidosis. Accepted for publication 7 December 1968.

2

GUNNARCLAUSEN ANDAMUNDERSLAND

In order to obtain a comparison to other diving mammals previously investigated or discussed by the present authors (CLAUSENand ERSLAND,1968), we have reinvestigated the respiratory properties of Cystophora blood in vitro by the same methods. Materials and methods The two seals available weighed about 50 kg and were about three months old (“blue backs”). The blood samples were obtained at one to two week intervals. Twenty to thirty ml of arterial blood was drawn into siliconed 10 ml syringes by puncturing a flipper artery. Heparin was used to prevent coagulation. The analyses began half an hour after sampling. The blood was stored in ice water during transport, later at + 4°C. Determination of O2 capacity and CO2 content, pH, Po2, Pco2, HbOz sat %, and Hb were made as described in a recent paper (CLAUSENand ERSLAND,1968). Hematocrit (Hct) was determined in triplicate or more, by 15 min centrifugation using a standard hematocrit centrifuge and capillary tubes (diam. 1.2-1.4, length 75 mm). (A stable Hct was obtained after less than 10 min centrifugation). Erythrocyte concentration (RBC) was determined by counting in Biirker chamber and by celloscope. The mean volume of the erythrocytes (MCV) was determined by constructing the PriceJones curve, using the celloscope 101 produced by Ljungberg et Co., Stockholm. The celloscope measurements were made immediately after dilution of whole blood in buffered physiological saline. The celloscope was adjusted to give a MCV of 85 p3 of human erythrocytes. The mean cell diameter (MCD) was obtained from the MCV/ MCD relation table published by Ljungberg et Co. in the celloscope instruction manual: MCD ,~6 MCVp3

6.8

7.5

8.2

8.9

9.6

10.3

71.5

85.0

102.5

122.0

143.0

164.0

The counting accuracy of the celloscope is N 1%. Since the erythrocytes of the Cystophora blood had a normal discoidal shape and appeared to have a normal morphology when studied by microscope, the mean cell diameter was also calculated as Hct/RBC* 10. Results and discussion The results listed in table 1 show that the high O2 capacity of the blood (36 vol %) is due to a high content of Hb (26.4 g/100 ml) having a normal O2 capacity (1.36 ml 0,/g Hb) at N 300 mm Hg of Oz. The Hb is held by erythrocytes which are 60 % larger than those of human blood in a 30% higher concentration than in human erythrocytes. The shape of the erythrocyte studied in buffered physiological saline by microscope, appeared normal as compared to that of human blood. In fig. 1 the HbOz dissociation curve is presented. It was constructed from the data in table 2. Figure 2 demonstrates the Bohr effect. The Bohr factor (AlogT,,/A pH) was - 0.66 (- 0.71 and - 0.62 in seal 1 and 2 respectively). Tse at pH 7.4 was 24.2 mm Hg, i.e. about 5-10 mm Hg lower than the in viuo values of SCHOLANDER’S investigation on the same species. The difference in the position of his and the present curves should

BLOOD OF THB BLADDERNOSE SEAL TABLE

3

1

Characteristics of blood in three samples from each of the two specimens. Hb g/100 ml

Hct %

RBC million/n-ma

Oa cap. vol 0%

MCV ya

MCD

celloscope

Hct/RBC

10

26.4

63

4.8

36

135

131

9.3

(25.8-28.4)

(60-67)

(4.3-5.3)

(34-38)

(131-138)

(127-W)

(9.2-9.4)

Red cell concentration

(RBC)

Mean cell volume (MCV)

was determined by celloscope

Mean cell diameter (MCD)

in two samples only.

gives the mean value and range of both methods.

TABLE 2 COZ and Oa tensions, HbOa sat % and pH of the blood. SEAL

1

Pco,

N

PH

40mmHg Po*

Pco, sat%

N

PH

105mmHg Po,

Pco, sat %

ff

PH

21 mmHg Po,

sat%

7.415

15.1

30.1

7.155

25.6

30.1

7.550

15.5

38.0

7.425

21.7

43.0

7.13s

38.4

51.5

7.545

28.9

64.0

1.405

28.2

62.0

7.140

49.4

67.5

7.535

35.7

77.0

1.385

41.3

76.0

7.130

55.1

77.0

-

-

-

7.390

15.3

29.5

7.140

26.0

31.5

7.560

15.7

41.0

7.410

22.0

49.0

7.190

32.0

42.0

7.510

22.5

55.5

7.360

28.7

54.0

7.160

44.0

60.0

7.510

29.4

73.0

7.370

35.2

72.5

7.135

56.0

73.0

-

-

SEAL

Pco,

2 N

40mmHg

Pco,

N

105 mm Hg

Po,

sat %

PH

7.340

15.1

26.5

7.095

19.7

24.5

7.340

21.7

44.0

7.085

31.6

41.5

7.320

34.9

71.0

7.095

43.4

64.0

7.280

61.1

90.0

7.070

55.2

PH

7.375

-

PO*

15.2

30.0

7.140

19.9

sat %

Pco, -.

N

21 mm Hg PO*

sat %

7.460

15.5

35.5

7.455

29.0

65.5

-

-

-

16.5

-

-

-

24.5

7.495

15.6

35.0

PH

7.375

21.8

45.5

7.130

25.8

34.5

7.480

22.4

53.5

7.360

35.0

74.0

7.130

31.8

47.5

7.475

29.2

67.0

-

-

-

7.130

43.7

65.5

-

-

-

-

-

-

7.105

55.6

77.0

-

-

-

GUNNAR CLAUSEN AND AMUND ERSLAND

Hb sat. %

80 -

60 -

I

I

I

1

20

1

40

’

I

1

I

60

80

Po2 mm

Hg

Fig. 1. The HbOa dissociation curve at 40 mm Hg of COa and pH 7.4, constructed from the data in table 2. For comparison the HbOa-Pao, dissociation curves obtained during submersion (SCHOLANDER, 1940) have been entered.

I

L

7.1

I

I

1

1

.2

.3

.4

.5

.6 PH Fig. 2. The TWJ-pHrelation demonstrating the Bohr effect. Squares: seal No. 1; circles: seal No. 2.

express the alveolar arterial tension difference of 0, (P&,-Pao,). This is especially interesting since SCHOLANDER’Sdata were obtained during submersion when the heart rate - and blood flow through the lungs - is about 10 % of normal owing to the profound bradycardia associated with submersion. SCHOLANDER’S curves are progressively displaced rightwards at falling Po2, because of the increasing Pco, and lactate

BLOOD OF THE BLADDERNOSE SEAL

3

5

40 PC0 mmM 2

Fig. 3. Characteristic COa dissociation curves of fully reduced and oxygenated blood (from seal No. 2).

TABLE 3 Blood pH and ~01% COs when Hb (26.6 go& is fully reduced and oxygenated Pco,

mm Hg 20.9

39.1 48.9 62.8

Hb

(Seal No.2).

HbOa

pH

COa

pH

COa

7.480 7.340 7.300 7.240

26.6 38.2 42.7 41.5

7.380 7.260 7.205 7.140

19.6 29.8 34.3 39.2

APH

ACOa

0.10 0.08 0.10 0.10

7.0 8.4 8.4 8.3

concentration in the blood. SCHOLANDER presents Pco, values corresponding to the HbO, dissociation curves. Using the present pH-log P,o, line and Bohr effect factor, T,, at pH 7.4 is 27.5 (26-30) mm Hg. Due to a slight lactate accumulation in the blood, that has not been accounted for in this calculation, the T,,-, must be somewhat lower than 27.5 mm Hg, i.e. the Pbl-Pao, is less than 4 mm Hg at TSo. A relatively high Haldane effect of 8.4 ~01% of CO, was found at 40 mm Hg of COz (fig. 3). The ACO, (Hb-HbO,) vol%/g Hb is 0.32, slightly lower than that of human blood (0.35). The buffering capacity of the blood (A[HCO;]/ApH) was - 36. meq/L at 26.6 g % Hb, i.e. higher than in human blood. The pH-log Po-,z lines that are shown in fig. 4, in comparison with that of human blood of equal Hb content, show that pH in re-

GUNNAR

CLAUSENAND

AMUND

ERSLAND

‘CO, mm Hg 120 -

20 -

t

I

I

I

I

I

I

20

1

.2

.3

x

.5

.6 pH

Fig.4.The pH-log PCO, lines made from the data in table 3 in comparison of equal Hb content (26.6 g%).

with that of human blood

duced blood, measured when making the CO2 dissociation curves, was 0.1 units higher than in oxygenated blood at constant Pco, (c$ table 3). Generally, the 0, capacity, Haldane effect and buffering capacity of C~,rtophoru blood appear to be modified as should be expected according to the high Hb content of the blood. A high Hb content, giving both high O2 capacity and buffering capacity, may be regarded as a valid adaptation to diving. The question of possible adaptations of the respiratory properties of mammalian blood to diving was discussed in a recent paper (CLAUSEN and ERSLAND, 1968). Acknowledgement

We wish to thank the Norwegian Fisheries Research Institute, Directorate Fisheries, which provided - and helped us with handling - the seals.

of

References CLAUSEN,G. and A. ER~LAND(1968). The respiratory properties of the blood of two diving rodents, the beaver and the water vole. Respir. Physiol. 5: 350-359. FLORKIN, M. and A. C. REDFIELD(1931). On the respiratory function of the blood of the sea lion. Biol. Bull. Woods Hole 61: 422-426. IRVING,L., 0. M. SOLANT,D. Y. SOLANTand K. G. FNJER (1935). Respiratory characteristics of the blood of the seal. J. Cell. Comp. Physiol. 6: 393-403. SCHOLANDER, P. F. (1940). Experimental investigations on the respiratory function in diving mammals and birds. Hvalrdd. Skr. 22: l-131.