HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (31) Citing Articles via Google Scholar Google Scholar Articles by Wu, B. J. Articles by Else, P. L. Search for Related Content PubMed PubMed Citation Articles by Wu, B. J. Articles by Else, P. L.

INFLAMMATION AND CYTOKINES

Membrane lipids and sodium pumps of cattle and crocodiles: an experimental test of the membrane pacemaker theory of metabolism

Departments of ¹Biomedical Science and ²Biological Science, Metabolic Research Centre, University of Wollongong, Wollongong, New South Wales, Australia 2522

Submitted 23 September 2003 ; accepted in final form 11 May 2004

The influence of membrane lipid composition on the molecular activity of a major membrane protein (the sodium pump) was examined as a test of the membrane pacemaker theory of metabolism. Microsomal membranes from the kidneys of cattle (Bos taurus) and crocodiles (Crocodylus porosus) were found to possess similar sodium pump concentrations, but cattle membranes showed a four- to fivefold higher enzyme (Na⁺-K⁺-ATPase) activity when measured at 37°C. The molecular activity of the sodium pumps (ATP/min) from both species was fully recoverable when delipidated pumps were reconstituted with membrane from the original source (same species). The results of experiments involving species membrane crossovers showed cattle sodium pump molecular activity to progressively decrease from 3,245 to 1,953 (P < 0.005) to 1,031 (P < 0.003) ATP/min when subjected to two cycles of delipidation and reconstitution with crocodile membrane as a lipid source. In contrast, the molecular activity of crocodile sodium pumps progressively increased from 729 to 908 (P < 0.01) to 1,476 (P = 0.01) ATP/min when subjected to two cycles of delipidation and reconstitution with cattle membrane as a lipid source. The lipid composition of the two membrane preparations showed similar levels of saturated (31–34%) and monounsaturated (23–25%) fatty acids. Cattle membrane had fourfold more n-3 polyunsaturated fatty acids (11.2 vs. 2.9%) but had a reduced n-6 polyunsaturate content (29 vs. 43%). The results support the membrane pacemaker theory of metabolism and suggest membrane lipids and their polyunsaturates play a significant role in determining the molecular activity of the sodium pump.

endotherms; ectotherms; sodium-potassium-adenosinetriphosphatase; [³H]ouabain binding; reconstitution; metabolism

This article has been cited by other articles:

				I. Walter and F. Seebacher Endothermy in birds: underlying molecular mechanisms J. Exp. Biol., August 1, 2009; 212(15): 2328 - 2336. [Abstract] [Full Text] [PDF]

				J. C. L. Brown, A. R. Gerson, and J. F. Staples Mitochondrial metabolism during daily torpor in the dwarf Siberian hamster: role of active regulated changes and passive thermal effects Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2007; 293(5): R1833 - R1845. [Abstract] [Full Text] [PDF]

				A. J. Hulbert, R. Pamplona, R. Buffenstein, and W. A. Buttemer Life and Death: Metabolic Rate, Membrane Composition, and Life Span of Animals Physiol Rev, October 1, 2007; 87(4): 1175 - 1213. [Abstract] [Full Text] [PDF]

				M. Pierre, M.-O. Husson, R. L. Berre, J.-L. Desseyn, C. Galabert, L. Beghin, C. Beermann, A. Dagenais, Y. Berthiaume, B. Cardinaud, et al. Omega-3 polyunsaturated fatty acids improve host response in chronic Pseudomonas aeruginosa lung infection in mice Am J Physiol Lung Cell Mol Physiol, June 1, 2007; 292(6): L1422 - L1431. [Abstract] [Full Text] [PDF]

				K. T. Murphy, A. C. Petersen, C. Goodman, X. Gong, J. A. Leppik, A. P. Garnham, D. Cameron-Smith, R. J. Snow, and M. J. McKenna Prolonged submaximal exercise induces isoform-specific Na+-K+-ATPase mRNA and protein responses in human skeletal muscle Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2006; 290(2): R414 - R424. [Abstract] [Full Text] [PDF]

				N. Turner, P. L. Else, and A. J. Hulbert An allometric comparison of microsomal membrane lipid composition and sodium pump molecular activity in the brain of mammals and birds J. Exp. Biol., January 15, 2005; 208(2): 371 - 381. [Abstract] [Full Text] [PDF]

				N. Turner, K. L. Haga, A. J. Hulbert, and P. L. Else Relationship between body size, Na+-K+-ATPase activity, and membrane lipid composition in mammal and bird kidney Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2005; 288(1): R301 - R310. [Abstract] [Full Text] [PDF]