期刊
JOURNAL OF APPLIED PHYSIOLOGY
卷 106, 期 3, 页码 865-870出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.90879.2008
关键词
dorsal horn; muscle contraction; blood pressure
资金
- National Heart, Lung, and Blood Institute [R01 HL075533, R01 HL078866, 0840130N, R01 HL060800]
Li J, Lu J, Gao Z, Koba S, Xing J, King N, Sinoway L. Spinal P2X receptor modulates muscle pressor reflex via glutamate. J Appl Physiol 106: 865-870, 2009. First published January 8, 2009; doi:10.1152/japplphysiol. 90879.2008.-Static contraction of skeletal muscle evokes reflex increases in blood pressure and heart rate. Previous studies showed that P2X receptors located at the dorsal horn of the spinal cord play a role in modulating the muscle pressor reflex. P2X stimulation can alter release of the excitatory amino acid, glutamate (Glu). In this report, we tested the hypothesis that stimulation of P2X receptors enhances the concentrations of Glu ([Glu]) in the dorsal horn, and that blocking P2X receptors attenuates contraction-induced Glu increases and the resultant reflex pressor response. Contraction was elicited by electrical stimulation of the L-7 and S-1 ventral roots of 14 cats. Glu samples were collected from microdialysis probes inserted in the L-7 level of the dorsal horn of the spinal cord, and dialysate [Glu] was determined using the HPLC method. First, microdialyzing alpha,beta-methylene ATP (0.4 mM) into the dorsal horn significantly increased [Glu]. In addition, contraction elevated [Glu] from baseline of 536 +/- 53 to 1,179 +/- 192 nM (P < 0.05 vs. baseline), and mean arterial pressure by 39 +/- 8 mmHg in the control experiment. Microdialyzing the P2X receptor antagonist pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (10 mM) into the dorsal horn attenuated the contraction induced-Glu increase (610 +/- 128 to 759 +/- 147 nM; P > 0.05) and pressor response (16 +/- 3 mmHg, P < 0.05 vs. control). Our findings demonstrate that P2X modulates the cardiovascular responses to static muscle contraction by affecting the release of Glu in the dorsal horn of the spinal cord.
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