Arginine vasopressin increases intracellular calcium ion concentration in isolated mouse collecting tubule cells: distinct mechanism of action through V2 receptor, but independent of adenylate cyclase activation.
The effects of arginine vasopressin (AVP*2) and its V2 receptor agonist, 1-deamino-8-D-AVP (dDAVP), on the intracellular calcium ion concentration ([Ca2+]i) in isolated collecting tubular cells of mouse kidney were examined using fluorescent indicator fura-2 and a superfusion system. Both AVP and dDAVP evoked a rapid, transient increase followed by a sustained elevation of [Ca2+]i in CCT, OMCT, and IMCT in a dose-dependent manner. In CCT, the increments in [Ca2+]i by dDAVP were lower than those induced by AVP at all concentrations (10(-10)-10(-6) M) of the agonists tested, while in OMCT and IMCT, the increments were comparable. The initial peak of the rise in [Ca2+]i induced by AVP and dDAVP in these collecting tubule segments was partially attenuated by about 40% and the second sustained elevation was largely abolished in the absence of Ca2+ in the superfusate. Further, the increments [Ca2+]i induced by AVP were not affected by the addition of nicardipine to the superfusate. The increases in [Ca2+]i evoked by AVP and dDAVP were not mimicked by cAMP or forskolin. Moreover, they were not affected by alpha-adrenergic stimulation with epinephrine, in the presence and absence of prazosin, conditions which inhibit AVP-dependent cAMP production. These results indicate that AVP increases [Ca2+]i in CCT, OMCT, and IMCT, probably through V2 receptors, but via a mechanism which is independent of adenylate cyclase activation. In addition, the rise in [Ca2+]i is due to both Ca2+ release from the intracellular stores and increased Ca2+ influx through Ca2+ channels insensitive to nicardipine.
Naruse
M
M
Third Department of Internal Medicine, Kumamoto University Medical School.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D007685:Kidney Tubules, Collecting / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin
D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D000262:Adenylyl Cyclases; D003894:Deamino Arginine Vasopressin; D002118:Calcium