Effect of divalent cations on KCl- and noradrenaline-induced contractile responses in rat aorta after nifedipine treatment.
Nifedipine (1 microM) relaxed the sustained contractile responses induced by 1 microM noradrenaline or 60 mM KCl in rat aortic strips. After washing, a second addition of the spasmogens gave smaller tonic contractions than the first one. Even more, a third addition of KCl also gave a smaller contraction than the first one, but a complete recovery of the contractile response to noradrenaline was obtained by a third addition of this agonist. Application of cumulative amounts of Ca2+ or Ba2+ (2.4-24 mM) on the residual contraction in response to these agents after nifedipine treatment, but in the absence of the blocker, restored the magnitude of the contractile responses. Addition of cumulative amounts of Mg2+ (2.4-24 mM) did not modify or even relax the contractile responses to KCl and noradrenaline, respectively.
Noguera
M A
MA
Department de Farmacologia, Facultat de Farmàcia, Universitat de València, Burjassot, Spain.
Chuliá
S
S
Ivorra
M D
MD
D'Ocon
M P
MP
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D002317:Cardiovascular Agents / Q000494:pharmacology*; D002413:Cations, Divalent / Q000494:pharmacology*; D066298:In Vitro Techniques; D007552:Isotonic Solutions / Q000494:pharmacology; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D002317:Cardiovascular Agents; D002413:Cations, Divalent; D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D011189:Potassium Chloride; D009543:Nifedipine; D002118:Calcium; D009638:Norepinephrine