title: Functional evidence for the regulation of cytosolic Ca2+ activity via V1A-receptors and beta-adrenoceptors in rat CCD.
abstract: In freshly isolated rat CCD segments, the effects of arginine vasopressin (AVP), oxytocin (OT), adrenaline (Ad), and their specific receptor agonists and antagonists on the intracellular Ca2+ activity ([Ca2+]i) were measured using the Ca2+ sensitive dye Fura-2 as fluorescence indicator. We observed that AVP, the V1-receptor agonist [Phe2Orn8] vasotocin ([Phe2]OVT), and OT increased [Ca2+]i biphasically. AVP (n = 9) and OT (n = 8) induced increases in [Ca2+]i were completely blocked by the V1A-receptor antagonist d(CH2)5Tyr(Me)2AVP. However, neither the V2-receptor agonist [Val4-D-Arg8]AVP (100 nM, n = 5), nor the OT-receptor agonist [Thr4,Gly7]OT (100 nM, n = 5) nor forskolin (1 microM, n = 4 and 10 microM, n = 5) did significantly change [Ca2+]i. Ad and the beta-adrenoceptor agonist isoproterenol (ISO) increased [Ca2+]i, which was not mimicked by the alpha 2-adrenoceptor agonist clonidine (1 microM, n = 10) or the alpha 1-adrenoceptor agonist phenylephrine (1 microM, n = 5). The beta-adrenoceptor antagonist propranolol (1 microM) completely blocked this Ad (1 microM, n = 4) induced [Ca2+]i increase. Insulin (INS 10 nM, n = 8), endothelin (ET 1 microM, n = 6), and angiotensin II (Ang II 1 pM to 10 nM; each n = 4) had no significant effect on [Ca2+]i. Considering the present results we propose a V1A-receptor and beta-adrenoceptor dependent modulation of [Ca2+]i in rat CCD.
authors.affiliation: Medizinische Poliklinik, Westfälische Wilhelms-Universität, Münster, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Ankorina-Stark
authors.forename: S
authors.initials: S
authors.lastname: Haxelmans
authors.forename: E
authors.initials: E
authors.lastname: Schlatter
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D046508:Culture Techniques; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D007672:Kidney Cortex / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D017483:Receptors, Vasopressin / Q000819:agonists / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D004791:Enzyme Inhibitors; D011943:Receptors, Adrenergic, beta; D017483:Receptors, Vasopressin; D014667:Vasopressins; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D007545:Isoproterenol; D002118:Calcium; D004837:Epinephrine