A novel role for GABA and glutamate in pericyte-mediated regulation of medullary blood flow

GABA and its synthesising enzyme, glutamate decarboxylase, have been detected in the rat kidney [1–2]. GABA has also been found in human plasma and urine [3–4] and most recently, a renoprotective role for GABA has been suggested [5]. We are systematically investigating functional roles for GABA and glutamate in the mammalian kidney.

Contractile pericytes regulate vasa recta diameter in response to a number of endogenous vasoactive agents and in doing so regulate medullary blood flow (MBF) [6]. We have utilised the live kidney slice model [6] to demonstrate GABA-mediated constriction of vasa recta that was significantly greater at pericyte sites than at non-pericyte sites (p< 0.01). Conversely, the GABA substrate glutamate (100 ?M) caused a significantly greater vasodilation of vasa recta at pericyte sites compared to non-pericyte sites (p< 0.05).

Data presented here identifies a novel role for GABA and glutamate in pericyte-mediated regulation of vasa recta diameter and thus MBF.