Regulation of right atrial beta-adrenoceptors after cardiopulmonary resuscitation in pigs.

Abstract

to test the hypothesis that right atrial beta-adrenoceptors are down-regulated after CPR and administration of beta-adrenergic agents. after 3 min of ventricular fibrillation and 3 min of cardiac massage, 6 pigs received adrenaline (45 micrograms/kg) intravenously before defibrillation. After restoration of spontaneous circulation, dopamine was given in order to maintain the mean arterial blood pressure stable. Right atrial beta-adrenergic binding sites were determined by an equilibration binding assay using (-)-125Iodocyanopindolol. plasma adrenaline (mean +/- S.E.M.) was 1.1 +/- 0.9 ng/ml (6.0 +/- 4.9 nmol/l) pre-arrest and increased to 63.8 +/- 45.8 (348.2 +/- 250.0 nmol/l) (P < 0.05) and 1034 +/- 344 ng/ml (5644 +/- 1878 nmol/l) (P < 0.05) during CPR before and after adrenaline administration. At points in time 30 and 120 min after successful CPR, plasma adrenaline was 2.4 +/- 0.5 and 1.3 +/- 0.3 ng/ml (13.1 +/- 2.7 and 7.1 +/- 1.6 nmol/l). Compared to pre-arrest, the density of high-affinity beta-adrenoceptors was 29.0 +/- 12.8 fmol/mg pre-arrest and was 69.4 +/- 21.6 and 84.2 +/- 16.7 fmol/mg (P < 0.05 vs. pre-arrest) 30 and 120 min after CPR. The density of low-affinity as well as of total binding sites was not significantly changed after CPR. it is concluded that markedly elevated plasma catecholamine concentrations after CPR and administration of adrenaline and dopamine do not lead to a decrease in the total density of beta-adrenoceptors but to an increase in high-affinity beta-adrenoceptors in right atrial cells.