The effect of γ-aminobutyric acid on the adrenergically induced vasoconstriction in the isolated perfused rat kidney

We examined the effect of γ-aminobutyric acid (GABA) on vasoconstriction induced by electrical stimulation (ES) of the renal nerves in the isolated pump-perfused rat kidney. ES (1-3 Hz) increased perfusion pressure and renal norepinephrine (NE) output in a frequency-dependent manner. Prasosin (10 and 30 nM) markedly inhibited the increases in perfusion pressure induced by ES. GABA (3 and 10μM) attenuated the increases in perfusion pressure and the NE output induced by ES. Exogenous NE (10, 30 and 60 nM) also elevated the perfusion pressure, but GABA faled to affect the NE-induced response. These results suggest that GABA acts on the presynaptic site to suppress neurotransmitter release, and thereby attenuates vasoconstriction in the renal sympathetic nervous system.