Pharmacological evidence that GABA-induced relaxation of rat proximal duodenum longitudinal muscle depends on NKCC cotransporter activity and Ca influx.

γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in adult central nervous system (CNS) synapses, but it excites immature CNS neurons as well as neurons in the myenteric plexus. The present work aimed to determine whether GABA-induced nonadrenergic, noncholinergic (NANC) neuronal-mediated relaxation of the rat duodenum is dependent on the activity of Na K Cl cotransporters (NKCC) and requires calcium influx. In the presence of guanethidine (3 µmol/L), atropine (3 µmol/L), and indomethacin (1 µmol/L), relaxations induced by GABA (100 µmol/L), KCl (5-10 mmol/L) and electrical field stimulation (1-8 Hz, 2 ms, 60 V), but not those induced by bradykinin (10-100 nmol/L) were abolished by lidocaine (300 µmol/L).

Inhibitory effect of Pyr6 (an Orai channel blocker) on agonist-induced contractions in rat uterus.

Aim: Both human and rat myometrium express stromal interaction molecule (STIM) and Orai/transient receptor potential canonical (TRPC) proteins, which are components of plasma membrane Ca store-operated channels. There are reports that these proteins mediate agonist-induced Ca influx in cultured myometrial cells. In this study, we aimed to determine the effects of Pyr6, an Orai channel blocker, on different agonist-induced contractions in isolated segments of rat uterus.