In:
American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 289, No. 3 ( 2005-09), p. H1265-H1276
Abstract:
Exposure to microgravity leads to a sustained elevation in transmural pressure across the cerebral vasculature due to removal of hydrostatic pressure gradients. We hypothesized that ion channel remodeling in cerebral vascular smooth muscle cells (VSMCs) similar to that associated with hypertension may occur and play a role in upward autoregulation of cerebral vessels during microgravity. Sprague-Dawley rats were subjected to 4-wk tail suspension (Sus) to simulate the cardiovascular effect of microgravity. Large-conductance Ca 2+ -activated K + (BK Ca ), voltage-gated K + (K V ), and L-type voltage-dependent Ca 2+ (Ca L ) currents of Sus and control (Con) rat cerebral VSMCs were investigated with a whole cell voltage-clamp technique. Under the same experimental conditions, K V , BK Ca , and Ca L currents of cerebral VSMCs from adult spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were also investigated. K V current density decreased in Sus rats vs. Con rats [1.07 ± 0.14 ( n = 22) vs. 1.31 ± 0.28 ( n = 16) pA/pF at +20 mV ( P 〈 0.05)] and BK Ca and Ca L current densities increased [BK Ca : 1.70 ± 0.37 ( n = 23) vs. 0.88 ± 0.22 ( n = 19) pA/pF at +20 mV ( P 〈 0.05); Ca L : −2.17 ± 0.21 ( n = 35) vs. −1.31 ± 0.10 ( n = 26) pA/pF at +10 mV ( P 〈 0.05)]. Similar changes were also observed in SHR vs. WKY cerebral VSMCs: K V current density decreased [1.03 ± 0.33 ( n = 9) vs. 1.62 ± 0.64 ( n = 9) pA/pF at +20 mV ( P 〈 0.05)] and BK Ca and Ca L current densities increased [BK Ca : 2.54 ± 0.47 ( n = 11) vs. 1.12 ± 0.33 ( n = 12) pA/pF at +20 mV ( P 〈 0.05); Ca L : −3.99 ± 0.53 ( n = 12) vs. −2.28 ± 0.20 ( n = 10) pA/pF at +20 mV ( P 〈 0.05)]. These findings support our hypothesis, and their impact on space cardiovascular research is discussed.
Type of Medium:
Online Resource
ISSN:
0363-6135
,
1522-1539
DOI:
10.1152/ajpheart.00074.2005
Language:
English
Publisher:
American Physiological Society
Publication Date:
2005
detail.hit.zdb_id:
1477308-9
SSG:
12
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