Vasopressin increases cytosolic free calcium concentration in glomerular mesangial cells
Bonventre, J.V.; Skorecki, K.L.; Kreisberg, J.I.; Cheung, J.Y.
American Journal of Physiology 251(1 Pt 2): F94-102
1986
ISSN/ISBN: 0002-9513 PMID: 3014901 Document Number: 281671
Cytosolic free calcium concentration ([Ca2+]f) was determined in cultured rat glomerular mesangial cells under basal conditions and after exposure to arginine vasopressin (AVP) or angiotensin II (ANG II). [Ca2+]f was determined using quin 2 or fura-2, two intracellular fluorescent probes. [Ca2+]f was measured to be 102 .+-. 3 nM (n = 154) using quin 2 and 82 .+-. 4 (n = 34) using fura-2. AVP and ANG II increased [Ca2+]f. Maximal levels of [Ca2+]f were achieved in < 10 s after addition of the hormone. This peak value was followed by a rapid fall toward the base line. With fura-2 as the intracellular Ca2+ indicator, [Ca2+]f increased from 74 .+-. 7 to a peak of 578 .+-. 39 nM (n = 17) with 100 nM AVP. At 115 s after addition of AVP, [Ca2+]f was 125 .+-. 9 nM. Similar peak levels of [Ca2+]f were observed using quin 2. The increase in [Ca2+]f was due in large part to release of Ca2+ from intracellular stores, since reduction in extracellular free [Ca2+] with EGTA did not prevent the hormone-induced increase in [Ca2+]f, although it did result in a decreased peak level and a more rapid return to base line. The AVP-induced increase in [Ca2+]f was blocked by the V1 receptor antagonist (CH2)5Tyr(Me)VDAVP. Neither isoproterenol, which increased adenylate cyclase activity, nor dibutyryl cAMP had any affect on [Ca2+)f directly or on the AVP-induced increase in [Ca2+)f. In this report we present the first direct measurements of [Ca2+)f and hormone-induced changes in [Ca2+]f in glomerular mesangial cells. We conclude that AVP increased [Ca2+]f by interaction with a cellular V1 receptor with subsequent mobilization of intracellular Ca2+ stores. This increase in [Ca2+]f is likely an intracellular mediator of AVP-induced contraction and prostaglandin production in the mesangial cell.