Izumisawa, Yu Tanaka-Yamamoto, Keiko Ciriello, John Kitamura, Naoki Shibuya, Izumi 2024-01-19T20:34:53Z 2024-01-19T20:34:53Z 2021-09-02 2019-02-01 0006-8993 https://pubs.kist.re.kr/handle/201004/120372 Characteristics of subfornical organ (SFO) neurons were examined by measuring the cytosolic Ca2+ concentration ([Ca2+](i)) in acutely dissociated neurons of the rat. SFO neurons, defined by the responsiveness to 50 mM K+ (n = 67) responded to glutamate (86%), angiotensin II (All) (50%), arginine vasopressin (AVP) (66%) and/or carbachol (CCh) (61%), at their maximal concentrations, with marked increases in [Ca2+](i). More than a half (174/307) of SFO neurons examined exhibited spontaneous Ca2+ oscillations, while the remainder showed a relatively stable baseline under unstimulated conditions. Spontaneous Ca2+ oscillations were suppressed when extracellular Ca2+ was removed and were inhibited when extracellular Na+ was replaced with equimolar N-methyl-D-glucamine. Ca2+ oscillations were unaffected by the inhibitor of Ca2+-dependent ATPases cyclopiazonic acid, the N-type Ca2+ channel blocker omega-conotoxin GVIA and the P/Q-type Ca2+ channel blocker omega-agatoxin IVA, but significantly inhibited by the high-voltage-activated Ca2+ channel blacker Cd2+ and the L-type Ca2+ channel blocker nicardipine. Ca2+ oscillations were also completely arrested by the voltage-gated Na+ channel blocker tetrodotoxin in 50% of SFO neurons but only partially in the remaining neurons. These results suggest that SFO neurons exhibit spontaneous membrane Ca2+ oscillations that are dependent in part on Ca2+ entry through L-type Ca2+ channels, whose activation may result from burst firing. Moreover, All at picomolar concentrations induced Ca2+ oscillations in neurons showing no spontaneous Ca2+ oscillations, while spontaneous Ca2+ oscillations were arrested by gamma-aminobutyric acid (10 mu M), suggesting that rises in [Ca2+](i) during Ca2+ oscillations may play an important role in the modulation of SFO neuron function. English ELSEVIER SENSORY CIRCUMVENTRICULAR ORGANS CENTRAL ROLES CALCIUM VASOPRESSIN RECEPTORS NUCLEUS BRAIN CURRENTS RELEASE INCREASES The cytosolic Ca2+ concentration in acutely dissociated subfornical organ (SFO) neurons of rats: Spontaneous Ca2+ oscillations and Ca2+ oscillations induced by picomolar concentrations of angiotensin II Article 10.1016/j.brainres.2018.10.005 1 BRAIN RESEARCH, v.1704, pp.137 - 149 BRAIN RESEARCH 1704 137 149 scie scopus 000457508100015 2-s2.0-85054558118 Neurosciences Neurosciences & Neurology Article SENSORY CIRCUMVENTRICULAR ORGANS CENTRAL ROLES CALCIUM VASOPRESSIN RECEPTORS NUCLEUS BRAIN CURRENTS RELEASE INCREASES Subfornical organs Angiotensin II Ca2+ imaging