Premium
Evidence that depletion of internal calcium stores sensitive to noradrenaline elicits a contractile response dependent on extracellular calcium in rat aorta
Author(s) -
Noguera M. Antonia,
D'Ocon M. Pilar
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb13892.x
Subject(s) - calcium , extracellular , aorta , endocrinology , medicine , chemistry , biology , microbiology and biotechnology
1 Noradrenaline 1 μ m induced a contractile response in rat isolated aorta in the presence or in the absence of extracellular Ca 2+ with depletion of intracellular Ca 2+ stores. Thereafter, during incubation in the presence of Ca 2+ , an increase in the resting tone was observed. Such a contractile response did not occur after exposure to caffeine or 5‐hydroxytryptamine. 2 This increase in tension was inhibited in a concentration‐dependent manner by α‐adrenoceptor antagonists (prazosin, phentolamine and yohimbine), the non‐specific relaxing compound, papaverine and by the Ca 2+ ‐entry blocker, nifedipine. Therefore, this contractile process is related to depletion of Ca 2+ stores sensitive to noradrenaline and is linked to Ca 2+ entry through voltage‐operated Ca 2+ channels and α‐adrenoceptors. 3 Phentolamine and yohimbine did not block the Ca 2+ refill pathway; prazosin and nifedipine inhibited the reuptake of Ca 2+ by an internal store sensitive only to noradrenaline; papaverine inhibited the refilling of caffeine‐ and noradrenaline‐sensitive Ca 2+ ‐stores.