AI Article Synopsis
- Nifedipine effectively relaxed sustained contractions in rat aortic strips caused by noradrenaline and high potassium levels (KCl).
- After initial contractions were diminished with nifedipine, subsequent applications of noradrenaline restored the contractile response, but the response to KCl was diminished with repeated exposures.
- Adding calcium or barium increased the residual contractions after nifedipine treatment, while magnesium did not affect the contractile responses to either noradrenaline or KCl.
Article Abstract
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.
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| http://dx.doi.org/10.1016/s0306-3623(98)00260-2 | DOI Listing |
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