CA-O-SENSING RECEPTOR (CAR)-MEDIATED ACTIVATION OF K-DEFICIENT MOUSE NEURONS( CHANNELS IS BLUNTED IN CAR GENE)

The extracellular Ca2+ (Ca-o)-sensing receptor (CaR) is expressed in h ippocampus and other brain regions, suggesting that it could mediate s ome of the well recognized but poorly understood direct actions of Ca- o on neuronal function. This study presents evidence that the CaR is f unctionally coupled to Ca2+-activated K+ channels. The effects of CaR agonists on these channels in neurons from wild type (WT) and CaR-defi cient (CaR -/-) mice were compared. Neomycin (100 mM) and elevation of Ca-o from 0.5 to 3 mM significantly increased the probability of chan nel opening (Po) in neurons from WT but not in those from CaR -/- mice . Thus the CaR activates neuronal K+ channels and could potentially in hibit neuronal excitability and neurotransmission via membrane repolar ization.