title: Intracellular Ca2+ release in flow-induced contraction of venous smooth muscle.
abstract: We designed the present study to determine whether Ca2+ release from intracellular stores contributes to flow-induced contraction. We carried out experiments on segments of rabbit facial vein under isometric conditions. Intraluminal flow by perfusion of physiological salt solution (10 to 80 microL/min) caused contraction in this vessel, which was significantly inhibited by (1) 30-minute pretreatment with 10 mumol/L ryanodine, the sarcoplasmic reticulum Ca2+ channel opener, and (2) 30-minute pretreatment with concomitant application of 20 mmol/L caffeine and 1 mumol/L cyclopiazonic acid in Ca(2+)-free medium to deplete the sarcoplasmic reticulum. In comparison, contraction initiated by 300 nmol/L histamine was significantly attenuated by the same interventions. K+ (25 mmol/L)-induced contraction was unaffected by ryanodine but was reduced after depletion of the sarcoplasmic reticulum. The phospholipase C inhibitor 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (10 mumol/L) inhibited contractions induced by flow and histamine but not by K+. These findings indicate that Ca2+ release from intracellular stores, presumably via the phosphatidylinositol pathway, contributes to flow- and histamine- but not raised K(+)-induced contractions in this vessel.
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002219:Carbamates / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007537:Isometric Contraction; D008297:Male; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D048448:Phenylcarbamates; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012433:Ryanodine / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014680:Veins / Q000378:metabolism / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D002219:Carbamates; D004791:Enzyme Inhibitors; D007211:Indoles; D048448:Phenylcarbamates; C025508:2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate; D012433:Ryanodine; D002110:Caffeine; D012965:Sodium Chloride; D006632:Histamine; D010738:Type C Phospholipases; D011188:Potassium; D002118:Calcium; C000543:cyclopiazonic acid