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Capsaicin-induced Relaxation in Rabbit Coronary Artery

 Dongsoo YEON  ;  Seongchun KWON  ;  Youngho LEE  ;  Joongwoo LEEM  ;  Taicksang NAM  ;  Ducksun AHN 
 Journal of Veterinary Medical Science, Vol.63(5) : 499-503, 2001 
Journal Title
 Journal of Veterinary Medical Science 
Issue Date
4-Aminopyridine/pharmacology ; Animals ; Calcium/metabolism ; Capsaicin/analogs & derivatives* ; Capsaicin/antagonists & inhibitors ; Capsaicin/pharmacology* ; Coronary Vessels/drug effects* ; Coronary Vessels/physiology ; Dinoprost/pharmacology ; Drug Interactions ; Fluorescent Dyes/chemistry ; Fura-2/analogs & derivatives* ; Fura-2/chemistry ; In Vitro Techniques ; Isometric Contraction/drug effects ; Isometric Contraction/physiology ; Muscle Relaxation/drug effects* ; Muscle Relaxation/physiology ; Muscle, Smooth, Vascular/drug effects* ; Muscle, Smooth, Vascular/physiology ; Peptides/pharmacology ; Potassium Channel Blockers ; Potassium Channels/physiology ; Rabbits ; Ruthenium Red/pharmacology
In the present study mechanism of inhibitory effects of capsaicin on the contractility of rabbit coronary artery were studied by measurement of isometric tension and intracellular Ca2+ concentration. Capsaicin (1 μM to 30 μM) relaxed the coronary artery pre-contracted with prostaglandin (PG) F2α (1 μM) in a concentration-dependent manner. The PGF2 α-induced increase in intracellular Ca2+ concentration was also inhibited. The effects of capsaicin were readily reversed by washing capsaicin from the bath. Capsaicin-induced relaxation was not attenuated by pretreatment with capsazepine (1 μM), a blocker of vanilloid receptor or ruthenium red (1 μM), a blocker of non-selective cation channel. Previous exposure to a high concentration of capsaicin (100 μM) or repeated application of capsaicin did not eliminate the relaxation response to subsequent application of capsaicin. Increasing the external K+ concentration to 80 mM significantly attenuated the capsaicin-induced relaxation with simultaneous change in intracellular Ca2+ concentration. Pretreatment with iberiotoxin (100 nM), a blocker of Ca2+-activated K+ channel, only partially inhibited the capsaicin-induced relaxation. However, application of 4-aminopyridine (4-AP, 1 mM), a blocker of delayed rectifier K+ current significantly inhibited the capsaicin-induced relaxation with concomitant attenuation of the effect on intracellular Ca2+ concentration. These results indicate that capsaicin may have a direct relaxing effect on the smooth muscle contractility, and relaxation may be due to activation of the 4-AP-sensitive, delayed rectifier K+ channels in the rabbit coronary artery.
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1. College of Medicine (의과대학) > Dept. of Physiology (생리학교실) > 1. Journal Papers
Yonsei Authors
Nam, Taick Sang(남택상)
Ahn, Duk Sun(안덕선) ORCID logo https://orcid.org/0000-0001-9351-6951
Lee, Young Ho(이영호) ORCID logo https://orcid.org/0000-0002-5749-1045
Leem, Joong Woo(임중우) ORCID logo https://orcid.org/0000-0002-1605-2230
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