Modification of cardiovascular response of adenosine A(2) receptor agonistby adenylate cyclase in the spinal cord of rats

This study was performed to investigate the influence of spinal adenosine A (2) receptors on the central regulation of blood pressure (BP) and heart ra te (HR), and to define whether its mechanism is mediated by adenylate cycla se or guanylate cyclase. Intrathecal (i.t.) administration of drugs at the thoracic level were performed in anesthetized, artificially ventilated ma l e Sprague-Dawley rats. Injection (i.t.) of adenosine A(2) receptor agonist, 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA; 1, 2 and 3 nmol) produced a dose dependent decrease of BP and HR. Pretreatment with adenylate cyclase inhibitor, MDL-12,330, attenuated the depressor and bradycardiac effects of CPCA (2 nmol), but not with guanylate cyclase inhibitor, LY-83,583. These results suggest that adenosine A(2) receptor in the spinal cord plays an in hibitory role in the central cardiovascular regulation and that the depress or and bradycardiac actions are mediated by adenylate cyclase. (C) 2000 Els evier Science Ireland Ltd. All rights reserved.