RT Journal Article
SR Electronic
T1 THE INFLUENCE OF RESERPINE PRETREATMENT ON THE CONTRACTILE AND METABOLIC EFFECTS PRODUCED BY OUABAIN ON ISOLATED RABBIT LEFT ATRIA
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 205
OP 211
VO 147
IS 2
A1 Levy, Joseph V.
A1 Richards, V.
YR 1965
UL http://jpet.aspetjournals.org/content/147/2/205.abstract
AB Pretreatment of rabbits with reserpine (1.0 mg/kg i.v.) significantly attenuated the positive inotropic response of electrically driven isolated left atria to a nontoxic concentration of ouabain (8.3 x 10-7 M) as measured by both per cent and absolute change in force. However, the absolute maximum contraction force (in grams) developed by the reserpinized atria was not significantly different from that seen in the normal atria. Reserpine pretreatment (5.0 mg/kg i.v.) did not prevent the toxic effects of ouabain (3.35 x l0-6 M). Chronic (3.0 mg/kg i.p. for 3 days) or acute reserpinization did not affect oxygen consumption of isolated left atria. In vitro reserpinization (1.0 and 10.0 γg/ml) also failed to affect atrial O2 consumption compared to controls. Reserpine pretreatment, either in vivo or in vitro did not modify the normal stimulatory effect of ouabain (2.8 x 10-6 M) on atrial O2 consumption. In addition, dichloroisoproterenol (DCI) in a concentration reported to block the positive inotropic effects of ouabain on the cat papillary muscle failed to modify the usual ouabain-induced augmentation of atrial O2 consumption. The data presented here and elsewhere are generally compatible with the view that the modification of the contractile responses to nontoxic concentrations of ouabain in appropriately reserpinized muscle is due in part to the absence or unavailability of endogenous catecholamines required for the production of ouabain-induced augmentation of contraction. However, other changes caused by reserpinization cannot be excluded as factors possibly contributing to the altered ouabain effects. Our data are not consonant with time hypothesis timat an altered oxidative metabolism resulting from reserpinization is involved in the attenuation of the contraction responses to nontoxic concentrations of ouabain in rabbit atrial tissue. The Williams & Wilkins Comapny