LACK OF ALTERATION IN CARDIAC BETA-ADRENOCEPTOR SITE CONCENTRATION IN RATS TREATED WITH AN ADENYLATE CYCLASE-STIMULATING DOSE OF ENDOTOXIN

In previous experiments on male rats we showed that 2 mg kg-1, intravenously, lipopolysaccharide from Escherichia coli, a sublethal nonhypotensive dose, induced circulating cardiodepressant activity, maximal alterations in steroid hormonal response, and myocardial adenylate cyclase hyperactivity 4 h later. The purpose of the present study was to investigate a possible relation between this adenylate cyclase hyperactivity and alterations in total ventricular beta-adrenoceptors. To this end, ventricular beta-adrenoceptor concentration and affinity were measured under the same conditions. Binding assays were performed using [H-3]dihydroalprenolol. No significant change was observed in both parameters.