cardiovascular-agents and ryodipine

The study covered 20 patients with angina pectoris. Antianginal drugs such as sydnopharm, kordafen, anaprilin, nitrosorbide, and foridon were tested by using pair exercise tests. All the patients had preliminary instrumental studies, including exercise test, echocardiography, hyperventilation and orthostatic tests, and variation pulsometry. A regression equation was derived, which could predict the efficacy of foridon from the findings of the tests used. The antianginal effect of foridon was found to be the weakest among the other drugs under study.

Topics: Angina Pectoris; Blood Pressure; Cardiovascular Agents; Echocardiography; Exercise Test; Heart Rate; Humans; Male; Middle Aged; Nifedipine; Prognosis; Respiratory Function Tests

2,6-Dimethyl-3,5-dimethoxycarbonyl-4-(o-difluoromethoxyphenyl)-1,4 -dihydropyridine (ryodipine, PP-1466), an effective Ca2+ channel blocker, diminishes contraction force and decreases duration of action potential in the frog heart ventricle strips. Dissociation constants K0.5 are 2 x 10(-7), 5 x 10(-7), and 10(-6) mol/l for PP-1466, nifedipine and nicardipine, respectively (at 0.25-0.3 Hz stimulation). One molecule of PP-1466 or nifedipine apparently interacts with two receptors on the channel (n = 0.5), nicardipine with one receptor (n = 1). The binding energy of PP-1466 and nifedipine increases at closed and diminishes at open channels which is in contrast to nicardipine, whose effect is irreversible. Thus, the site of nicardipine action differs from that of PP-1466 and nifedipine. PP-1466 (10(-8) mol/l--10(-6) mol/l) suppresses contraction force and diminishes frequency of spontaneous contractions of the rabbit atria, and also displays antagonism to the effect of Ca2+ upon rabbit auricle contractions. In the isolated rabbit aorta and portal vein PP-1466 is more antagonistic to contractions caused by Ca2+ than by epinephrine. Both competitive and non-competitive types of antagonism can be distinguished.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Animals; Anura; Calcium Channel Blockers; Cardiovascular Agents; Cattle; Dihydropyridines; Electric Stimulation; Electrophysiology; Heart; In Vitro Techniques; Mitochondria; Mitochondria, Liver; Mitochondrial Swelling; Muscle Contraction; Muscle, Smooth, Vascular; Myocardial Contraction; Nicardipine; Nifedipine; Pyridines; Rabbits; Rats