ISSN:
1432-2013
Keywords:
Key words Weak acid
;
Smooth muscle
;
pH
;
Osmolarity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract In vitro both acetate and hyperosmolarity cause vasodilation, which could be physiologically important during food ingestion and during peritoneal dialysis. The purpose of this study was to investigate the role of the intracellular calcium concentration ([Ca2+]i, measured with fura-2), membrane potential (measured with glass microelectrodes) and intracellular pH [pHi, measured with bis-carboxyethylcarboxyfluorescein (BCECF)] in the vasodilation. Hyperosmolar sodium acetate (30 mM) concentration dependently relaxed noradrenaline-precontracted arteries. This response was associated with hyperpolarization and a fall in [Ca2+]i. In arteries precontracted with 50 mM K+ the relaxation was associated with a decrease of [Ca2+]i but no change in membrane potential. Isoosmolar sodium acetate neither relaxed or affect [Ca2+]i of K+-precontracted arteries, but induced a small relaxation with no reduction in [Ca2+]i in noradrenaline-precontracted arteries. Hyperosmolar acetate caused a transient reduction of pHi that was unrelated to relaxation. It is concluded that the mechanisms responsible for the relaxation to hyperosmolar acetate involve a decrease of [Ca2+]i, which is only partly explained by hyperpolarization and probably a decrease in the sensitivity of the contractile proteins to [Ca2+]i. pHi seems not to play a role in these effects.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004240050692
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