쥐 척수후각세포의 유해자극 반응에 대한 칼슘이온통로 차단제의 억제작용

• 영문명: Calcium Channel Blockers Suppress the Responses of Rat Dorsal Horn Cell to Nociceptive Input
• 발행기관: 대한생리학회-대한약리학회
• 저자명: 신홍기(Hong Kee Shin) 강석한(Sok Han Kang) 김기순(Kee Soon Kim)
• 간행물 정보: 『The Korean Journal of Physiology & Pharmacology』제1권 제6호, 625~637쪽, 전체 13쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1997.01.01

영문 초록

Calcium ions are implicated in a variety of physiological functions, including enzyme activity, membrane excitability, neurotransmitter release, and synaptic transmission, etc. Calcium antagonists have been known to be effective for the treatment of exertional angina and essential hypertension. Selective and nonselective voltage-dependent calcium channel blockers also have inhibitory action on the acute and tonic pain behaviors resulting from thermal stimulation, subcutaneous formalin injection and nerve injury. This study was undertaken to investigate the effects of iontophoretically applied Ca^⁢⁢ and its antagonists on the responses of WDR (wide dynamic range) cells to sensory inputs. The responses of WDR cells to graded electrical stimulation of the afferent nerve and also to thermal stimulation of the receptive field were recorded before and after iontophoretical application of Ca^⁢⁢, EGTA, Mn^⁢⁢, verapamil, ω-conotoxin GVIA, ω-conotoxin MVIIC and ω-agatoxin IVA. Also studied were the effects of a few calcium antagonists on the C-fiber responses of WDR cells sensitized by subcutaneous injection of mustard oil (10%). Calcium ions and calcium channel antagonists (Mn^⁢⁢, verapamil, ω-conotoxin GVIA & ω-agatoxin IVA) current-dependently suppressed the C-fiber responses of WDR cells without any significant effects on the A-fiber responses. But ω-conotoxin MVIIC did not have any inhibitory actions on the responses of WDR cell to A-fiber, C-fiber and thermal stimulation. Iontophoretically applied EGTA augmented the WDR cell responses to C-fiber and thermal stimulations while spinal application of EGTA for about 20∼30 min strongly inhibited the C-fiber responses. The augmenting and the inhibitory actions of EGTA were blocked by calcium ions. The WDR cell responses to thermal stimulation of the receptive field were reduced by iontophoretical application of Ca^⁢⁢, verapamil, ω-agatoxin IVA, and ω-conotoxin GVIA but not by ω-conotoxin MVIIC. The responses of WDR cells to C-fiber stimulation were augmented after subcutaneous injection of mustard oil (10%, 0.15 ml) into the receptive field and these sensitized C-fiber responses were strongly suppressed by iontophoretically applied Ca^⁢⁢, verapamil, ω-conotoxin GVIA and ω-agatoxin IVA. These experimental findings suggest that in the rat spinal cord, L-, N-, and P-type, but not Q-type, voltage-sensitive calcium channels are implicated in the calcium antagonist-induced inhibition of the normal and the sensitized responses of WDR cells to C-fiber and thermal stimulation, and that the suppressive effect of calcium and augmenting action of EGTA on WDR cell responses are due to changes in excitability of the cell.

키워드

Normal and sensitized WDR cell C fiber responses Thermal response Calcium channel antagonist Iontophoresis