Journal of Applied Physiology, Vol 80, Issue 1 298-306, Copyright © 1996 by American Physiological Society

ARTICLES

Splenic contraction, catecholamine release, and blood volume redistribution during diving in the Weddell seal

W. E. Hurford, P. W. Hochachka, R. C. Schneider, G. P. Guyton, K. S. Stanek, D. G. Zapol, G. C. Liggins and W. M. Zapol
Department of Anesthesia, Harvard Medical School, Boston, Massachusetts 02114.

The spleen of the Weddell seal (Leptonychotes weddelli) may contract and inject red blood cells (RBCs) into the peripheral circulation during diving, but evidence for this hypothesis is indirect. Accordingly, we measured splenic dimensions by ultrasonography, plasma catecholamine concentrations, hemoglobin concentration, and hematocrit in five Weddell seals before and after intravenous epinephrine during halothane anesthesia and while awake at the surface after voluntary dives. Spleen size was reduced immediately after epinephrine injection or after the seal surfaced. Within the first 2 min after the seal surfaced, cephalocaudal splenic length was 71 +/- 2% (mean +/- SD; P < 0.05) and splenic thickness was 71 +/- 4% (P < 0.05) of the maximal resting values. Splenic size increased (half-time = 6-9 min) after the seal surfaced and was inversely correlated with plasma epinephrine and norepinephrine concentrations. Hemoglobin concentration increased from 17.5 +/- 5.3 g/dl (measured during general anesthesia) to 21.9 +/- 3.7 g/dl (measured in the first 2 min after surfacing). At these same times, the hematocrit increased from 44 +/- 12 to 55 +/- 8%. These values decreased (half-time = 12-16 min) after the seal surfaced. We estimate 20.1 liters of RBCs were sequestered at rest, presumably in the spleen, and released either on epinephrine injection or during diving. Catecholamine release and splenic contraction appear to be an integral part of the voluntary diving response of Weddell seals.

This article has been cited by other articles:

				C. C. W. Hsia, R. L. Johnson Jr., D. M. Dane, E. Y. Wu, A. S. Estrera, H. E. Wagner, and P. D. Wagner The canine spleen in oxygen transport: gas exchange and hemodynamic responses to splenectomy J Appl Physiol, November 1, 2007; 103(5): 1496 - 1505. [Abstract] [Full Text] [PDF]

				T. K. Stockard, D. H. Levenson, L. Berg, J. R. Fransioli, E. A. Baranov, and P. J. Ponganis Blood oxygen depletion during rest-associated apneas of northern elephant seals (Mirounga angustirostris) J. Exp. Biol., August 1, 2007; 210(15): 2607 - 2617. [Abstract] [Full Text] [PDF]

				T. J. Wright and R. W. Davis The effect of myoglobin concentration on aerobic dive limit in a Weddell seal J. Exp. Biol., July 1, 2006; 209(13): 2576 - 2585. [Abstract] [Full Text] [PDF]

				G. G. Haddad Tolerance to low O2: lessons from invertebrate genetic models Exp Physiol, March 1, 2006; 91(2): 277 - 282. [Abstract] [Full Text] [PDF]

				R. Stephenson Physiological control of diving behaviour in the Weddell seal Leptonychotes weddelli: a model based on cardiorespiratory control theory J. Exp. Biol., May 15, 2005; 208(10): 1971 - 1991. [Abstract] [Full Text] [PDF]

				D. Bakovic, Z. Valic, D. Eterovic, I. Vukovic, A. Obad, I. Marinovic-Terzic, and Z. Dujic Spleen volume and blood flow response to repeated breath-hold apneas J Appl Physiol, October 1, 2003; 95(4): 1460 - 1466. [Abstract] [Full Text] [PDF]

				I. B. Stewart, D. E. R. Warburton, A. N. H. Hodges, D. M. Lyster, and D. C. McKenzie Cardiovascular and splenic responses to exercise in humans J Appl Physiol, April 1, 2003; 94(4): 1619 - 1626. [Abstract] [Full Text] [PDF]

				S. J. Thornton, D. M. Spielman, N. J. Pelc, W. F. Block, D. E. Crocker, D. P. Costa, B. J. LeBoeuf, and P. W. Hochachka Effects of forced diving on the spleen and hepatic sinus in northern elephant seal pups PNAS, July 31, 2001; 98(16): 9413 - 9418. [Abstract] [Full Text] [PDF]

				E. Schagatay, J. P. A. Andersson, M. Hallen, and B. Palsson Physiological and Genomic Consequences of Intermittent Hypoxia: Selected Contribution: Role of spleen emptying in prolonging apneas in humans J Appl Physiol, April 1, 2001; 90(4): 1623 - 1629. [Abstract] [Full Text] [PDF]

				R. Davis and S. Kanatous Convective oxygen transport and tissue oxygen consumption in Weddell seals during aerobic dives J. Exp. Biol., January 5, 1999; 202(9): 1091 - 1113. [Abstract] [PDF]

				I. Kuwahira, U. Kamiya, T. Iwamoto, Y. Moue, T. Urano, Y. Ohta, and N. C. Gonzalez Splenic contraction-induced reversible increase in hemoglobin concentration in intermittent hypoxia J Appl Physiol, January 1, 1999; 86(1): 181 - 187. [Abstract] [Full Text] [PDF]

				A. Cabanac, L. P. Folkow, and A. S. Blix Volume capacity and contraction control of the seal spleen J Appl Physiol, June 1, 1997; 82(6): 1989 - 1994. [Abstract] [Full Text] [PDF]

				K. Espersen, H. Frandsen, T. Lorentzen, I.-L. Kanstrup, and N. J. Christensen The human spleen as an erythrocyte reservoir in diving-related interventions J Appl Physiol, May 1, 2002; 92(5): 2071 - 2079. [Abstract] [Full Text] [PDF]