Reference

Comparative effects of two slow channel calcium entry blockers, FR 34235 and nifedipine, on true coronary collateral blood flow

Comparative effects of two slow channel calcium entry blockers, FR 34235 and nifedipine, on true coronary collateral blood flow. Gross, Garrett J.; Warltier, David C.; Hardman, Harold F. (Dep. Pharmacol. Toxicol., Med. Coll. Wisconsin, Milwaukee, WI 53226, USA). J. Cardiovasc. Pharmacol., 6(1), 61-7 (English) 1984. CODEN: JCPCDT. ISSN: 0160-2446. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) The effect of a new dihydropyridine Ca2+-entry blocker, FR 34235 (I) [75530-68-6], on coronary collateral blood flow was compared with that of nifedipine in anesthetized dogs following acute ligation of the left anterior descending coronary artery. During infusion of doses of both agents, which produced nearly equiv. decreases (15-20 mm Hg) in mean arterial pressure, flow was significantly increased in normal myocardium; however, no change in collateral perfusion to ischemic myocardium was obsd. When blood pressure was returned to control values by an aortic cuff, blood flow to the normal region further increased. Transmural flow to the ischemic region was also significantly increased by both compds. Nifedipine increased collateral flow primarily to the subepicardium, whereas FR 34235 increased collateral perfusion to the subepicardium, midmyocardium, and subendocardium. Thus, dihydropyridine Ca2+-entry blockers may increase collateral blood flow to ischemic myocardium if drug-induced hypotension is minimized. In addn., FR 34235 has a more favorable effect on the transmural distribution of blood flow than does nifedipine.

Relaxing effect of calcium antagonists and a-blocking agents on isolated dog coronary arteries

Relaxing effect of calcium antagonists and a-blocking agents on isolated dog coronary arteries. Yamaguchi, Kazuo (Med. Sch., Nagoya City Univ., Nagoya 467, Japan). Nagoya-shiritsu Daigaku Igakkai Zasshi, 37(4), 293-306 (Japanese) 1986. CODEN: NASDA6. ISSN: 0027-7606. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) Section cross-reference(s): 1 The structure of the smooth muscle of the coronary artery and the effects of various drugs on muscle contraction were examd. As in other smooth muscles, coronary artery smooth muscle was constructed of thick filaments (myosin) and fine filaments (actin). Surface vesicles were present on the cell membrane, and sarcoplasma. Dog arterial smooth muscle was contracted strongly by KCl, norepinephrine (I) [51-41-2], angiotensin II [11128-99-7], and PGF2a [551-11-1]. The Ca2+ antagonists FR-34235 [75530-68-6] and nifedipine [7440-09-7] suppressed smooth muscle contraction induced by KCl considerably but their effects on I-induced contraction were weaker. 88068-72-8 and 7440-09-7 which are cas registry numbers of chemicals are mentioned. The a-blocker SGB-1534 [88068-72-8] and prazosin [19216-56-9] did not suppress contractions induced by KCl, but strongly suppressed I-induced contraction. Similar suppressive effects for KCl- and I-induced contraction were exerted by the nonspecific vasodilator, nitroglycerin [55-63-0]. KCl and I increased Ca2+ influx, and the Ca2+ antagonists FR-34235 and nifedipine suppressed the increment. No such suppressive effect was shown by prasozin or nitroglycerin. .