Effect of dietary cimaterol on Na(+)-K+ ATPase activity in rabbit tissues

Cimaterol, a catecholamine analog that acts as a beta-adrenergic agonist, has been shown to have a growth promoting effect in rabbits. Catecholamines are also known to stimulate ion transport in many tissues. The objective of this study was to determine the effect of dietary cimaterol on rabbit tissue Na(+)-K+ ATPase activity. Twelve New Zealand White rabbits, fed either control diet or cimaterol-supplemented diet, were killed at the end of a 35-d feeding trial. Heart, kidney, and liver were weighed, and total ATPase and Na(+)-K+ ATPase activities of these tissues were determined. Cimaterol did not affect liver and kidney weights, but heart weight was significantly increased. Cimaterol increased both total and Na(+)-K+ ATPase activities in heart and kidney but had no effect in liver. These data indicate that increased dietary energy intake and body energy expenditure in cimaterol-fed animals can be attributed, in part, to elevated Na(+)-K+ ATPase activities in heart and kidney.