Effects of the novel water-soluble calcium antagonist (+/-)-3-(4-allyl-1-piperazinyl)-2,2-dimethylpropyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylate dihydrochloride on the responses of isolated canine arteries.

The effects of NKY-722 ((+/-)-3-(4-allyl-1-piperazinyl)-2,2-dimethylpropyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylate dihydrochloride, CAS 117241-46-0), a new water soluble dihydropyridine derivative on the responses of isolated canine arteries were examined. NKY-722 (IC50: 5-16 x 10(-10) mol/l), nicardipine (IC50: 5-10 x 10(-10) mol/l) and nifedipine (IC50: 44-195 x 10(-10) mol/l) relaxed four arteries in the potency order of basilar > coronary > mesenteric > intrarenal arteries. NKY-722 was nearly equipotent to nicardipine and about 10 times more potent than nifedipine. [3H]NKY-722 was accumulated in the four arteries in the same order of amount as the vasoinhibitory effect. All three drugs inhibited the contraction induced by Ca2+ and methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylophenyl)-p yri dine-5- carboxylate (Bay K 8644) in the mesenteric arteries, indicating their Ca2+ antagonistic actions. NKY-722 and nicardipine were nearly equipotent and about 100 times more potent than nifedipine on the Ca(2+)-induced contraction and was about 4 times more potent than nicardipine and 400 times more potent than nifedipine on the Bay K 8644-induced contraction. NKY-722, nicardipine and nifedipine relaxed the mesenteric arteries precontracted with KCl by more than 90%, while they relaxed the arteries contracted with PGF2 alpha, 9,11-dideoxy-9 alpha, 11 alpha-methanoepoxy-PGF2 alpha (U-46619) and endothelin-1 only by 40-70%. The IC50 values of NKY-722 and nicardipine were similar and much smaller than that of nifedipine for all four contracting agents.(ABSTRACT TRUNCATED AT 250 WORDS)