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PLoS One. 2011;6(5):e19775. doi: 10.1371/journal.pone.0019775. Epub 2011 May 18.

Differential regulation and recovery of intracellular Ca2+ in cerebral and small mesenteric arterial smooth muscle cells of simulated microgravity rat.

Author information

1
Department of Aerospace Clinical Medicine, Key Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China.

Abstract

BACKGROUND:

The differential adaptations of cerebrovasculature and small mesenteric arteries could be one of critical factors in postspaceflight orthostatic intolerance, but the cellular mechanisms remain unknown. We hypothesize that there is a differential regulation of intracellular Ca(2+) determined by the alterations in the functions of plasma membrane Ca(L) channels and ryanodine-sensitive Ca(2+) releases from sarcoplasmic reticulum (SR) in cerebral and small mesenteric vascular smooth muscle cells (VSMCs) of simulated microgravity rats, respectively.

METHODOLOGY/PRINCIPAL FINDINGS:

Sprague-Dawley rats were subjected to 28-day hindlimb unweighting to simulate microgravity. In addition, tail-suspended rats were submitted to a recovery period of 3 or 7 days after removal of suspension. The function of Ca(L) channels was evaluated by patch clamp and Western blotting. The function of ryanodine-sensitive Ca(2+) releases in response to caffeine were assessed by a laser confocal microscope. Our results indicated that simulated microgravity increased the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in cerebral VSMCs, whereas, simulated microgravity decreased the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in small mesenteric VSMCs. In addition, 3- or 7-day recovery after removal of suspension could restore the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases to their control levels in cerebral and small mesenteric VSMCs, respectively.

CONCLUSIONS:

The differential regulation of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in cerebral and small mesenteric VSMCs may be responsible for the differential regulation of intracellular Ca(2+), which leads to the altered autoregulation of cerebral vasculature and the inability to adequately elevate peripheral vascular resistance in postspaceflight orthostatic intolerance.

PMID:
21611118
PMCID:
PMC3097196
DOI:
10.1371/journal.pone.0019775
[Indexed for MEDLINE]
Free PMC Article

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