In:
American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 274, No. 6 ( 1998-06-01), p. F1006-F1014
Abstract:
Effects of extracellular ATP on intracellular free calcium concentration ([Ca 2+ ] i ) were examined in rat single nephron segments using the fura 2-AM. ATP (10 μM) induced a significant transient increase in [Ca 2+ ] i in the glomerulus, the early proximal convoluted tubule (S1), the cortical collecting tubule (CCT), and the outer medullary collecting tubule (OMCT). The magnitude of the response was the greatest in the OMCT among four segments. ATP induced an increase in the [Ca 2+ ] i in a dose-dependent manner in S1 and OMCT. In the OMCT, ATP caused a biphasic increase in [Ca 2+ ] i consisting of an initial rapid rise and a sustained phase. Removal of calcium from the medium resulted in an attenuation of the sustained phase of [Ca 2+ ] i and an ∼30% reduction in the height of the initial [Ca 2+ ] i peak in response to 10 μM ATP. Effects of ATP, its analogs, and its metabolites were tested in the S1 and OMCT. ATP, 2-methylthio-ATP (2-MeS-ATP), ADP, and UTP increased [Ca 2+ ] i dose dependently. AMP and adenosine did not affect [Ca 2+ ] i in the S1 and OMCT. The ATP- or 2-MeS-ATP-induced [Ca 2+ ] i increase was inhibited by the pretreatment of the S1 and OMCT with suramin or reactive blue 2. Neomycin, a phospholipase C inhibitor, attenuated the ATP-induced [Ca 2+ ] i increase. To investigate the hormonelike action of ATP in OMCT, a heterologous cross desensitization was performed. The pretreatment of OMCT with ATP inhibited increases in vasopressin-, ANG II-, endothelin-1-, or bradykinin-induced [Ca 2+ ] i increase. These findings suggest that ATP might affect the above peptidyl agonist-activated calcium mobilizations.
Type of Medium:
Online Resource
ISSN:
1931-857X
,
1522-1466
DOI:
10.1152/ajprenal.1998.274.6.F1006
Language:
English
Publisher:
American Physiological Society
Publication Date:
1998
detail.hit.zdb_id:
1477287-5
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