Mechanism of vasopressin-induced increase in intracellular Ca2+ in LLC-PK1 porcine kidney cells.
Analysis of the signal transduction cascade of vasopressin-induced increase in intracellular Ca2+ concentration ([Ca2+]i) in LLC-PK1 cells was performed. First, a comparison of the effect of vasopressin on [Ca2+]i in LLC-PK1 cells with that produced in rat hepatocytes was performed [an intracellular mobilizing mechanism involving a V1 receptor coupled to the production of inositol 1,4,5-trisphosphate (IP3)]. Second, the effect of known inhibitors of intracellular Ca2+ mobilization on vasopressin Ca2+ response in LLC-PK1 cells was studied. Vasopressin induced a transient increase in [Ca2+]i in both LLC-PK1 cells and hepatocytes. In contrast to the single [Ca2+]i spike seen in LLC-PK1 cells, vasopressin induced an average of two to three [Ca2+]i spikes in hepatocytes. The V1 antagonist (Pmp1-O-Me-Tyr2-[Arg8]vasopressin, 1 microM) abolished vasopressin Ca2+ response in both cell types. Inhibitors of intracellular Ca2+ mobilization, thapsigargin (5 microM) and U-73122 (3 microM), abolished the Ca2+ response by vasopressin in LLC-PK1 cells. The results suggest that vasopressin-induced increase in [Ca2+]i in LLC-PK1 cells is mediated via a V1-like receptor and involves the mobilization of intracellular Ca2+ through an IP3- or thapsigargin-sensitive Ca2+ pool.
Dibas
A I
AI
Department of Pharmacology, University of North Texas Health Science Center at Fort Worth, 76107, USA.
Rezazadeh
S M
SM
Vassan
R
R
Mia
A J
AJ
Yorio
T
T
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002451:Cell Compartmentation / Q000187:drug effects; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D018374:LLC-PK1 Cells; D008099:Liver / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017483:Receptors, Vasopressin / Q000502:physiology; D015398:Signal Transduction; D013552:Swine; D019284:Thapsigargin / Q000494:pharmacology; D014667:Vasopressins / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D004963:Estrenes; D011760:Pyrrolidinones; D017483:Receptors, Vasopressin; D014667:Vasopressins; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D003994:Bucladesine; D019284:Thapsigargin; D002118:Calcium