BRADYKININ DEPOLARIZES THE RAT ISOLATED SUPERIOR CERVICAL-GANGLION VIA B-2 RECEPTOR ACTIVATION

Experiments were undertaken to characterise the action of kinins on sympathetic neurones of the rat superior cervical ganglion (SCG) by use of in vitro grease-gap, extracellular recording techniques in conjunction with selective agonists and antagonists for B-1 and B-2 bradykinin (BK) receptors. Superfusion of BK (10 nM to 10 mu M) to the ganglion produced a concentration-related depolarisation (pD(2) = 7.02 +/- 0.04, n = 7) which was inhibited by the selective B-2 antagonist HOE 140 (10-100 nM), but not by the B-1 antagonist Leu(8)desArg(9) BK (1 mu M), indomethacin (7 mu M) or the nitric oxide synthase inhibitor L-N-G-nitroarginine methyl ester (300 mu M). DesArg(9)BK (10 nM to 10 mu M) had no effect on membrane potential. Pre-treatment of animals with intravenous bacterial lipolysaccharide (LPS, 3 mg kg(-1)) failed to induce B-1 receptor-mediated depolarisations of SCG neurones, or change responses to BK (P > 0.05, n = 4). These experiments highlight and characterise the action of BK as a neuromodulator of sympathetic neurones via B-2 receptor activation.