Calcium signaling pathways utilized by P2X receptors in freshly isolated preglomerular MVSMC. Am J Physiol Renal Physiol 2001 Jun;280(6):F1054-61
Date
05/16/2001Pubmed ID
11352845DOI
10.1152/ajprenal.2001.280.6.F1054Scopus ID
2-s2.0-0034979794 (requires institutional sign-in at Scopus site) 43 CitationsAbstract
This study tested the hypothesis that P2X receptor activation increases intracellular Ca(2+) concentration ([Ca(2+)](i)) in preglomerular microvascular smooth muscle cells (MVSMC) by evoking voltage-dependent calcium influx. MVSMC were obtained and loaded with the calcium-sensitive dye fura 2 and studied by using single-cell fluorescence microscopy. The effect of P2X receptor activation on [Ca(2+)](i) was assessed by using the P2X receptor-selective agonist alpha,beta-methylene-ATP and was compared with responses elicited by the endogenous P2 receptor agonist ATP. alpha,beta-Methylene-ATP increased [Ca(2+)](i) dose dependently. Peak increases in [Ca(2+)](i) averaged 37 +/- 11, 73 +/- 15, and 103 +/- 21 nM at agonist concentrations of 0.1, 1, and 10 microM, respectively. The average peak response elicited by 10 microM alpha,beta-methylene-ATP was approximately 34% of the response obtained with 10 microM ATP. alpha,beta-Methylene-ATP induced a transient increase in [Ca(2+)](i) before [Ca(2+)](i) returned to baseline, whereas ATP induced a biphasic response including a peak response followed by a sustained plateau. In Ca(2+)-free medium, ATP induced a sharp transient increase in [Ca(2+)](i), whereas the response to alpha,beta-methylene-ATP was abolished. Ca(2+) channel blockade with 10 microM diltiazem or nifedipine attenuated the response to alpha,beta-methylene-ATP, whereas nonspecific blockade of Ca(2+) influx pathways with 5 mM Ni(2+) abolished the response. Blockade of P2X receptors with the novel P2X receptor antagonist NF-279 completely but reversibly abolished the response to alpha,beta-methylene-ATP. These results indicate that P2X receptor activation by alpha,beta-methylene-ATP increases [Ca(2+)](i) in preglomerular MVSMC, in part, by stimulating voltage-dependent Ca(2+) influx through L-type Ca(2+) channels.
Author List
White SM, Imig JD, Kim TT, Hauschild BC, Inscho EWMESH terms used to index this publication - Major topics in bold
Adenosine TriphosphateAnimals
Calcium
Calcium Channel Blockers
Calcium Signaling
Diltiazem
In Vitro Techniques
Kidney Glomerulus
Male
Muscle, Smooth, Vascular
Nickel
Rats
Rats, Sprague-Dawley
Receptors, Purinergic P2