Intracellular ANG II induces biological effects in nonrenal cells, but it is not known whether it plays a physiological role in renal proximal tubule cells (PTCs). PTCs express angiotensinogen, renin, and angiotensin-converting enzyme mRNAs, suggesting the presence of high levels of intracellular ANG II. We determined if microinjection of ANG II directly in single PTCs increases intracellular c...

Both stimulatory and suppressive responses of the sympathetic nervous system to angiotensin II (AII) have been reported in intact animals. To elucidate possible cellular mechanisms, we studied AII-induced changes in cytosolic Ca2+ ([Ca2+]i) in primary cultures of rat stellate ganglion neurons. Two different patterns of [Ca2+]i responses to AII were observed: dose-dependent increases in [Ca2+]i ...

1. Monitoring of [Ca2+]i and vasopressin secretion in isolated nerve endings from the rat neurohypophysis were studied to determine the relationship between the time course of vasopressin secretion and depolarization-induced changes in [Ca2+]i. 2. Membrane depolarization by increasing the extracellular [K+] led to concentration-dependent, parallel increases in the amount of vasopressin release ...

We investigated the role of intracellular calcium concentration ([Ca2+]i) in endothelin-1 (ET-1) production, the effects of potential vasospastic agents on [Ca2+]i, and the presence of L-type voltage-dependent Ca2+ channels in cerebral microvascular endothelial cells. Primary cultures of endothelial cells isolated from piglet cerebral microvessels were used. Confluent cells were exposed to eith...

The hydrogen ion is an important factor in the alteration of vascular tone in pulmonary circulation. Endothelial cells modulate vascular tone by producing vasoactive substances such as prostacyclin (PGI2) through a process depending on intracellular Ca2+ concentration ([Ca2+]i). We studied the influence of CO2-related pH changes on [Ca2+]i and PGI2 production in human pulmonary artery endotheli...

Perturbations of intracellular Ca2+ ion concentration ([Ca2+]i) have important effects on numerous neuronal processes and influence development and survival. Neuronal [Ca2+]i is, in large part, dependent on activity, and changes in activity levels can alter how neurons handle calcium (Ca). To investigate the ability of neuronal Ca homeostatic mechanisms to adapt to the persistent elevation of [...

A contractile property of phenylephrine (PE), alpha 1 agonist, on rat anococcygeus muscle was compared with that on rat aorta by simultaneously measuring changes in intracellular Ca2+ ([Ca2+]i) level and muscle tension. (1) PE (0.1-30 microM) and high K+ induced a sustained increases in [Ca2+]i level and muscle tension of both the muscles. (2) An application of verapamil (10 microM) and EGTA (4...

Changes in free cytosolic calcium were measured in UMR-106 cells in response to parathyroid hormone (PTH) stimulation. Bovine PTH-(1-34) induced an increase in [Ca2+]i with the contour of the rise in [Ca2+]i occurring in three successive phases: a rapid increase in [Ca2+]i occurring within seconds, rapid decrement in [Ca2+]i to near-resting levels within 1 min, and slow increment in [Ca2+]i. Ph...

We tested the hypothesis that cyclopiazonic acid (CPA), an inhibitor of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase, increases intracellular Ca2+ concentration ([Ca2+]) in aortic myocytes and that the increase in [Ca2+]i is higher in aortic cells from deoxycorticosterone acetate (DOCA)-hypertensive rats. Male Sprague-Dawley rats, 250-300 g, underwent uninephrectomy, received a silastic implan...

We used the calcium-sensitive fluorescent indicator quin 2 to monitor changes in cytosolic free calcium concentration ([Ca2+]i) associated with angiotensin II receptor activation in cultured vascular smooth muscle cells isolated from rat aorta. Resting [Ca2+]i in unstimulated vascular smooth muscle cells was 198 +/- 7 nM. Angiotensin II induced concentration-dependent rapid increases in [Ca2+]i...