title: The effect of cooling on the contractile response to endothelin-1 in small arteries from humans.
abstract: The pathogenesis of the prolonged cold-induced vasospasm of Raynaud's disease (RD) is unknown. Cooling has been shown to decrease the sensitivity of cutaneous rabbit ear arteries to endothelin-1 (ET-1), perhaps by increasing the availability of nitric oxide (NO). If the endothelium in RD lacks this NO-mediated inhibitory function during cooling, increased production and enhanced constriction to ET-1 could cause vasospasm. This study examined the effect of cooling on the contractile response to ET-1 in human microvessels. Small arteries were dissected from biopsy specimens of human fat and were cannulated in a small vessel arteriograph. Cumulative concentration-response curves to ET-1 (10(-12) to 3 x 10(-7) M) were obtained in vessels at 37 degrees C (n = 8) and 24 degrees C (n = 7). Cooling to 24 degrees C resulted in an eightfold decrease in sensitivity to ET-1 (EC50 6.6 +/- 2.5 x 10(-10) M at 37 degrees C vs. 5.5 +/- 2.5 x 10(-9) M at 24 degrees C; p < 0.05, unpaired t test). The Emax was not significantly different at 37 degrees C and 24 degrees C (114 +/- 9 at 37 degrees C vs. 138 +/- 14 at 24 degrees C; p = 0.18). These results suggest that cooling decreases the sensitivity of human microvessels to ET-1. Further investigation is needed to establish the mechanism of this effect, including studies in vessels obtained from patients with RD.
authors.affiliation: Department of Pharmacology, University of Edinburgh, Scotland.
authors.forename: P J
authors.initials: PJ
authors.lastname: Smith
authors.forename: D S
authors.initials: DS
authors.lastname: McQueen
authors.forename: D J
authors.initials: DJ
authors.lastname: Webb
mesh_terms: D000368:Aged; D001158:Arteries / Q000187:drug effects / Q000502:physiology; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D016232:Endothelins