Summary
We investigated the mechanism of vascular relaxation produced by denopamine (deno), an oral positive inotropic agent that has selective β1-adrenergic action. Deno concentration-dependently (0.1 µM–30 µM) relaxed ring segments of canine femoral, mesenteric, and renal arteries which were partially precontracted with 1 µm phenylephrine or norepinephrine, but did not relax those precontracted with 5 µM prostaglandin F2α or 40 mM K+. The relaxation was not significantly inhibited by pretreatment with 10 µM propranolol or metoprolol. Deno produced a parallel rightward shift in concentration-response curves to phenylephrine in femoral and renal arteries. The Schild plot yielded linear regressions of slopes of 1.301 ± 0.106 and 0.823 ± 0.122, respectively, which were not significantly different from unity. The pA2 values of Deno against phenylephrine in femoral and renal arteries were 5.41 ± 0.03 and 5.76 ± 0.06, respectively.
On the other hand, Deno concentration-dependently (10 nM–10 µM) relaxed ring segments of canine coronary arteries which were partially precontracted with 5 µM prostaglandin F2α. The relaxation was significantly inhibited by pretreatment with 10 µM metoprolol.
In conclusion, vascular smooth muscle relaxation by Deno was mediated through β1-adrenergic action in canine coronary arteries and through the blocking effect of α-adrenoceptors in canine femoral, mesenteric, and renal arteries.
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Aikawa, J., Moroi, M., Namiki, A. et al. Vascular relaxing mechanism of denopamine in isolated canine coronary, femoral, mesenteric, and renal arteries. Heart Vessels 8, 176–180 (1993). https://doi.org/10.1007/BF01744739
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DOI: https://doi.org/10.1007/BF01744739