Cardiovascular properties of MS-857, a new and potent cardiotonic agent, on normal and failing hearts.
The cardiovascular properties of MS-857 [4-acetyl-1-methyl-7-(4-pyridyl)-5,6,7,8-tetrahydro-3(2H)-isoquinolinone ], a novel cardiotonic agent, were investigated in anesthetized and conscious dogs. MS-857 (1-100 micrograms/kg i.v.) produced a significant and dose-dependent increase in cardiac contractility with relatively small changes in heart rate and blood pressure. This indicates a sizable separation between positive inotropic and other effects of MS-857. Oral administration of MS-857 to conscious dogs (0.1-1 mg/kg) also produced a sustained increase in cardiac contractility in a dose-dependent manner. The total duration of action was longer than 7 h at a dose of 1 mg/kg p.o. There occurred no arrhythmias and no changes in animal behavior. After chronic oral administration, MS-857 completely retained its activities, indicating the lack of tachyphylaxis. In the acute heart failure models induced by either propranolol or pentobarbital, MS-857 reversed the cardiac depressant effects of these drugs. Moreover, MS-857 also significantly improved the pentobarbital-induced heart failure in the heart-lung preparation. MS-857 did not inhibit the Na+, K+-ATPase, but inhibited the phosphodiesterase (PDE) III selectively, both of which were prepared from the dog ventricular muscle. Thus, MS-857 can be characterized as a potent nonsympathomimetic, nonglycoside cardiotonic drug with a selective inhibitory activity on PDE III. The cardiovascular properties revealed by this study strongly suggest that MS-857 will exert a beneficial effect in the treatment of congestive heart failure.
Maruyama
M
M
Institute of Biological Science, Mitsui Pharmaceuticals, Inc., Chiba, Japan.
Kamiya
J
J
Kaiho
T
T
Kobari
T
T
D000758:Anesthesia; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006321:Heart / Q000187:drug effects; D006333:Heart Failure / Q000139:chemically induced / Q000503:physiopathology*; D007546:Isoquinolines / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects; D008297:Male; D009206:Myocardium / Q000201:enzymology; D010424:Pentobarbital; D010727:Phosphoric Diester Hydrolases / Q000097:blood; D011433:Propranolol; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood; D013237:Stereoisomerism; D044005:Tetrahydroisoquinolines
D002316:Cardiotonic Agents; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; C059136:MS 857; D011433:Propranolol; D010727:Phosphoric Diester Hydrolases; D000254:Sodium-Potassium-Exchanging ATPase; D010424:Pentobarbital