Calcium sparks in the intact gerbil spiral modiolar artery. BMC Physiol 2011 Aug 26;11:15
Date
08/30/2011Pubmed ID
21871098Pubmed Central ID
PMC3170618DOI
10.1186/1472-6793-11-15Scopus ID
2-s2.0-80052022644 (requires institutional sign-in at Scopus site) 6 CitationsAbstract
BACKGROUND: Calcium sparks are ryanodine receptor mediated transient calcium signals that have been shown to hyperpolarize the membrane potential by activating large conductance calcium activated potassium (BK) channels in vascular smooth muscle cells. Along with voltage-dependent calcium channels, they form a signaling unit that has a vasodilatory influence on vascular diameter and regulation of myogenic tone. The existence and role of calcium sparks has hitherto been unexplored in the spiral modiolar artery, the end artery that controls blood flow to the cochlea. The goal of the present study was to determine the presence and properties of calcium sparks in the intact gerbil spiral modiolar artery.
RESULTS: Calcium sparks were recorded from smooth muscle cells of intact arteries loaded with fluo-4 AM. Calcium sparks occurred with a frequency of 2.6 Hz, a rise time of 17 ms and a time to half-decay of 20 ms. Ryanodine reduced spark frequency within 3 min from 2.6 to 0.6 Hz. Caffeine (1 mM) increased spark frequency from 2.3 to 3.3 Hz and prolonged rise and half-decay times from 17 to 19 ms and from 20 to 23 ms, respectively. Elevation of potassium (3.6 to 37.5 mM), presumably via depolarization, increased spark frequency from 2.4 to 3.2 Hz. Neither ryanodine nor depolarization changed rise or decay times.
CONCLUSIONS: This is the first characterization of calcium sparks in smooth muscle cells of the spiral modiolar artery. The results suggest that calcium sparks may regulate the diameter of the spiral modiolar artery and cochlear blood flow.
Author List
Krishnamoorthy G, Regehr K, Berge S, Scherer EQ, Wangemann PAuthor
Gayathri K. Natarajan Research Scientist II in the Anesthesiology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Aniline CompoundsAnimals
Arteries
Caffeine
Calcium
Calcium Signaling
Cochlea
Female
Gerbillinae
Membrane Potentials
Muscle, Smooth, Vascular
Phosphodiesterase Inhibitors
Potassium
Ryanodine Receptor Calcium Release Channel
Xanthenes