Schweda, Frank and Kraemer, Bernhard K. and Kurtz, Armin (2001) Differential roles of the sodium-calcium exchanger in renin secretion and renal vascular resistance. PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 442 (5). pp. 693-699. ISSN 0031-6768
Full text not available from this repository. (Request a copy)Abstract
The intracellular free calcium concentration ([Ca2+](i)) is a central regulator of renin secretion and the contractility of vascular smooth muscle cells. As [Ca2+](i) results from calcium influx and calcium extrusion, we were interested in the role of the Na+/Ca2+-exchanger as an important calcium-extrusion pathway in the regulation of renin secretion. Therefore, we investigated the effects of inhibiting the Na+/Ca2+-exchanger, either by reducing the extracellular sodium concentration ([Na+](e)) or using pharmacological tools, on renin secretion and vascular resistance in the isolated perfused rat kidney model. Stepwise reductions of [Na+](e) led to progressive (up to sevenfold) increases in renal vascular resistance ([Na+](e) 7 mM) whilst renin secretion rates were not altered significantly. Similarly, pharmacological blockade of the Na+/Ca2+-exchanger by benzamil (100 muM) or KB-R7943 (30 muM) resulted in significant vasoconstrictions without altering basal renin secretion rates. Also renin secretion that was pre-stimulated by isoproterenol (10 nM), blockade of macula densa salt transport by bumetanide (100 muM) or lowering the perfusion pressure to 40 mmHg was not attenuated by Na+/Ca2+-exchanger inhibition, although the vascular resistance increased significantly. In contrast, angiotensin II (100 pM) reduced pre-stimulated renin secretion values by 50%. The subsequent lowering of the [Na+](e) however did not augment the inhibition of renin secretion, although the renal vascular resistance increased markedly. We conclude that the Na+/Ca2+-exchanger has no functional role in the regulation of [Ca2+](i), in juxtaglomerular cells controlling renin secretion, whereas it markedly affects the preglomerular vascular smooth muscle cells of the renal vasculature.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SMOOTH-MUSCLE CELLS; IMMORTALIZED AORTIC MYOCYTES; NA+-CA2+ EXCHANGE; AFFERENT ARTERIOLES; NA+/CA2+ EXCHANGE; CYTOSOLIC CA2+; RAT-KIDNEY; RELEASE; INHIBITION; INFLUX; isolated perfused rat kidney; renin system; juxtaglomerular cell; Na+/Ca2+-exchanger |
| Subjects: | 500 Science > 570 Life sciences 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Innere Medizin II Biology, Preclinical Medicine > Institut für Physiologie > Prof. Dr. Armin Kurtz |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Dec 2021 13:13 |
| Last Modified: | 14 Dec 2021 13:13 |
| URI: | https://pred.uni-regensburg.de/id/eprint/41237 |
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