HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 289/3/H1265    most recent 00074.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Xie, M.-J. Articles by Cheng, H.-W. Search for Related Content PubMed PubMed Citation Articles by Xie, M.-J. Articles by Cheng, H.-W.

Functional alterations in cerebrovascular K⁺ and Ca²⁺ channels are comparable between simulated microgravity rat and SHR

Department of Aerospace Physiology, Fourth Military Medical University, Xi’an, China

Submitted 25 January 2005 ; accepted in final form 9 May 2005

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 Ca²⁺-activated K⁺ (BK_Ca), voltage-gated K⁺ (K_V), and L-type voltage-dependent Ca²⁺ (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.

postspaceflight cardiovascular deconditioning; hindlimb unloading; hypertension; cerebral vasculature; vascular smooth muscle cells; voltage-gated potassium channels; large-conductance calcium-activated potassium channels; voltage-dependent calcium channels

This article has been cited by other articles:

				J.-H. Xue, L.-F. Zhang, J. Ma, and M.-J. Xie Differential regulation of L-type Ca2+ channels in cerebral and mesenteric arteries after simulated microgravity in rats and its intervention by standing Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H691 - H701. [Abstract] [Full Text] [PDF]