title: Effect of acidosis on contraction, intracellular pH and calcium in the rabbit mesenteric small artery.
abstract: The purpose of the present study was to determine the effect of various types of acidosis on vessel diameter, intracellular pH (pHi), and calcium concentration ([Ca2+]i) in a cannulated preparation of the mesenteric arteriole of the rabbit. The effect of acidosis on vessel contraction was also studied in the wire-mounted preparation. In the cannulated preparation, pre-contracted by noradrenaline, hypercapnia caused vasoconstriction and increases in [Ca2+]i. In the wire-mounted preparation pre-contracted by either noradrenaline or high KCl, hypercapnia caused a transient vasoconstriction. In contrast, in the cannulated preparation pre-contracted by high KCl, hypercapnia caused a transient vasorelaxation and decreases in [Ca2+]i. Intracellular acidosis, induced by a NH4Cl prepulse, caused vasoconstriction and increases in [Ca2+]i even in the cannulated preparation pre-contracted by high KCl. The decrease in pHi during hypercapnia was similar to that observed after NH4Cl withdrawal. These data suggest that: (1) the effect of acidosis on vascular tone and [Ca2+]i is different depending upon the type of preparation and the mode of pre-activation, and (2) [Ca2+]i may, at least partly, regulate vascular contraction and relaxation during acidosis.
authors.affiliation: Department of Pediatric Cardiology, Tokyo Women's Medical College, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nakanishi
authors.forename: H
authors.initials: H
authors.lastname: Gu
authors.forename: K
authors.initials: K
authors.lastname: Momma
mesh_terms: D000138:Acidosis / Q000378:metabolism / Q000503:physiopathology*; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000378:metabolism; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism*; D010313:Partial Pressure; D011189:Potassium Chloride / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D011921:Rats, Inbred WKY; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D003470:Culture Media; D000643:Ammonium Chloride; D002245:Carbon Dioxide; D011189:Potassium Chloride; D002118:Calcium