The density of beta-adrenoreceptors in cardiac muscle membranes of muskrats and guinea pigs.
1. Cardiac membranes were prepared and then incubated with a range of concentrations of the beta-adrenergic ligand, dihydroalprenolol. Specific binding to the receptor was measured and receptor density and binding affinities were determined. 2. The receptor density was about 40% greater in the guinea pig heart than in the muskrat heart. The reduced beta-receptor density in the muskrat heart helps explain the previous findings of a lesser pumping ability and decreased responsiveness to isoproterenol in the muskrat compared with guinea pig hearts. 3. The decreased beta-receptor density may aid the muskrat in diving by reducing the oxygen consumption of the heart and thus prolonging diving time.
McKean
T A
TA
Department of Biological Sciences, University of Idaho, Moscow 83843.
D000818:Animals; D003411:Arvicolinae / Q000378:metabolism*; D004082:Dihydroalprenolol; D006168:Guinea Pigs; D009206:Myocardium / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013045:Species Specificity
D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol