Abstract
The supraoptic nucleus is neurosecretory cell which secretes oxytocin and vasopressin in the neurohypophysis. Slice patch clamp teqnique was applied in order to measure the whole cell currents and membrane potentials using male rat in postnatal 21-28. The supraoptic nucleus was identified under infra-red microscopy. Under current clamp condition, ATP application depolarized and after application, the firing frequency was suppressed. ATP application (100 μM) activated the rapid inward currents and slowly desensitized.at the holding potential of -50 mV. This inward current was blocked by P2 antagonist, suramin and pyridoxal - phosphate - 6 - azophenyl - 2' ,4'- disulfonate (PPADS). ATP analogue, a,b methylene ATP (100 μM) also evoked inward current. The peak values of a,b methylen ATP-evoked response showed 10-20% of those of ATP-evoked ones. After patch-clamp recording, suction was applied to aspirate the contents of the cell into the pipette. Subsequently, single cell RT-PCR analysis for all P2X subtypes was performed using harvested cytoplasm. Signal of P2X2 subtype was detected in cells which responded to ATP. In supraoptic nucleus, P2X2 subtype was mainly expressed and functioned. [Jpn J Physiol 54 Suppl:S130 (2004)]
