RT Journal Article SR Electronic T1 Pituitary Adenylate Cyclase-Activating Polypeptide Induces a Sustained Increase in Intracellular Free Ca2+Concentration and Catecholamine Release by Activating Ca2+Influx via Receptor-Stimulated Ca2+ Entry, Independent of Store-Operated Ca2+ Channels, and Voltage-Dependent Ca2+ Channels in Bovine Adrenal Medullary Chromaffin Cells JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 972 OP 982 DO 10.1124/jpet.102.033456 VO 302 IS 3 A1 Katsuya Morita A1 Akira Sakakibara A1 Shigeo Kitayama A1 Kei Kumagai A1 Kazuo Tanne A1 Toshihiro Dohi YR 2002 UL http://jpet.aspetjournals.org/content/302/3/972.abstract AB Characteristics of pituitary adenylate cyclase-activating polypeptide (PACAP)-induced increase of Ca2+ entry and catecholamine (CA) release were studied in bovine adrenal medullary chromaffin cells. PACAP induced intracellular free Ca2+concentration ([Ca2+]i), showing an initial transient [Ca2+]i rise followed by a sustained rise and CA release, which were not blocked by the blocking agents for nicotinic acetylcholine receptor (nAChR) channel, the voltage-dependent Ca2+ channel (VOC), or the Na+ channel. The sarcoendoplasmic Ca2+-ATPase inhibitors thapsigargin and cyclopiazonic acid did not affect the PACAP-induced sustained rise of [Ca2+]i, but did inhibit the initial [Ca2+]i rise. In cells pretreated with cyclopiazonic acid or membrane-permeable, low-affinity Ca2+ chelatorN′,N′,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine, PACAP further stimulated the entry of Ca2+ or Mn2+, whereas these treatments masked [Ca2+]i dynamics induced by bradykinin. PACAP-induced sustained [Ca2+]i rise and Mn2+ entry were enhanced by acidic extracellular solution and reduced by alkalinization, whereas thapsigargin-induced Mn2+ entry was regulated by the opposite. PACAP-induced [Ca2+]i rise and Mn2+ entry were not affected by blockers of cAMP-dependent protein kinase, phospholipase C, or protein kinase C. All store-operated Ca2+ channel (SOC) blocking agents tested inhibited thapsigargin-induced Mn2+ entry. 1{β-[3-(4-Methoxyphenyl)-propoxy]-4-methoxyphenylethyl}-1H-imidazole hydrochloride (SK&F 96365), (R,S)-(3,4-dihydro-6,7-dimethoxy-isoquinoline-1-yl)-2-phenyl-N,N-di-[2-(2,3,4-trimethoxyphenyl)ethyl]-acetamide, and econazole inhibited PACAP-induced Ca2+ or Mn2+ entry, whereas GdCl3, 7,8-benzoflavone, nor-dihydroguaiaretic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid, fulfenamic acid, and niflumic acid did not. SK&F 96365 and econazole but not GdCl3 inhibited PACAP-induced CA release. These results suggest that PACAP activates a novel Ca2+entry pathway associated with sustained CA release independent of the nAChR channel, VOC and SOC, activated by acid pH, with different sensitivity to blockers of SOC. This pathway may provide a useful model for the study of receptor-operated Ca2+ entry. The American Society for Pharmacology and Experimental Therapeutics