Bradykinin elevates cytosolic Ca2+ concentration in smooth muscle cells isolated from rat duodenum.
The effect of bradykinin on the cytosolic Ca2+ concentration were measured in single, Fura-2 loaded, smooth muscle cells isolated from rat duodenum. All cells responded with a Ca2+ signal when exposed to bradykinin. The bradykinin response consisted of an initial Ca2+ spike followed by a plateau. Pre-treatment of single muscle cells with either the phospholipase C blocker U-73122 or thapsigargin, which is a potent inhibitor of the endoplasmic reticulum Ca2+-ATPase, inhibited the response to bradykinin. Pre-treatment of the cells with EGTA or La3+ to inhibit the Ca2+ influx, abolished the response induced by bradykinin. We conclude that bradykinin applied to single smooth muscle cells from rat duodenum, increases cytosolic Ca2+ by emptying intracellular Ca2+ stores, and by contribution from extracellular Ca2+. In contrast to bradykinin-induced response in isolated rat duodenum (a relaxation followed by a contraction), we did not observe a biphasic effect of bradykinin on cytosolic Ca2+ in single muscle cells. Bradykinin may thus cause relaxation of duodenal smooth muscle indirectly through an effect on neighbouring cells as dilatation is brought about by this agent in blood vessels.
Wassdal
I
I
Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Norway.
Larsen
K
K
Iversen
J G
JG
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D003600:Cytosol / Q000378:metabolism; D004386:Duodenum / Q000187:drug effects* / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D004963:Estrenes; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D004533:Egtazic Acid; D019284:Thapsigargin; D007811:Lanthanum; D010738:Type C Phospholipases; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D002118:Calcium