PubMed Health⌕ Search

Biomedical subjects

Y Nakagawa

Publications and source records attributed to Y Nakagawa.

At least 37 records · Page 2Linked to original sources
PubMed1979

Effects of niludipine (Bay a 7168) on the cardiovascular system with a note on its calcium-antagonistic effects.

1,4-Dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylic acid-bis-(2-propoxyethyl)-ester (niludipine, Bay a 7168), a newly synthesized vasodilator, was three to ten times more potent than nifedipine in dilating the coronary artery of the canine heart-lung and isolated fibrillating heart preparations, but had weaker direct cardiac depressant effects. This drug had a strong and highly selective calcium antagonistic effect on the smooth muscle and also had stronger vasodilating activity on renal and femoral vascular beds as compared to nifedipine. It inhibited myocardial oxidative metabolism in canine and guinea pig hearts.

Animals↗
PubMed1978

Multiple forms of carboxypeptidase Y from Saccharomyces cerevisiae. Kinetic demonstration of effects of carbohydrate residues on the catalytic mechanism of a glycoenzyme.

In the course of our further investigation of the active site titration of carboxypeptidase Y, using 4-nitrophenyl trimethylacetate, we have found that carboxypeptidase Y can be isolated in different molecular forms. Carboxypeptidase Y obtained from Fleischmann baker's yeast has a molecular weight of 53,000, as compared to 64,000 for an enzyme species isolated from Anheuser-Busch baker's yeast. The amino acid analyses of both enzymes were essentially identical and very similar to those reported by others. However, we have found that the molecular weight difference is due to a variation in carbohydrate content as determined by gas chromatography. When carboxypeptidase Y was isolated from a single source, Anheuser-Busch baker's yeast, we observed a smaller variation in carbohydrate content. In all cases, sugar analyses revealed only mannose and N-acetylglucosamine to be present. The effect of the enzyme's carbohydrate content on the "burst kinetics" of the 4-nitrophenyl trimethylacetate reaction has been examined. In general, the Anheuser-Busch enzyme, containing more carbohydrate than the Fleischmann enzyme, reacts with a larger apparent bimolecular rate constant, kcat/Km. On the other hand, the deacylation rate constant, k3, is affected only slightly.

Amino Acids↗
PubMed1978

[Alpha- and beta-adrenoceptor blocking actions of labetalol and effects on the myocardial function, coronary circulation and myocardial energy metabolism thereof (author's transl)].

In the isolated atria, trachea and aorta of the guinea pig and in the heart-lung preparation (HLP) of the dog, labetalol was 3.6 approximately 5.9 times less potent than phentolamine in blocking alpha-adrenoceptors, 1.4 approximately 3.6 times less potent as beta 1-blocker and 6 times less potent as beta 2-blocker than propranolol. Beta 1 and beta 2-blocking actions were 12 approximately 28 and 7 times more potent than alpha-blocking action, respectively. As regards beta 1-blockade, attenuation of the heart rate increase was more prominent than that of the augmentation of the contractile force. Both in the isolated atrial preparation of the guinea pig and in canine HLP, labetalol produced a positive inotropic and chronotropic effect and a slight increase in the coronary flow associated with a slight increase in the myocardial O2 consumption and improvement of the myocardial redox potential. Myocardial extraction and usage of lactate, pyruvate and glucose tended to be decreased and those of FFA decreased significantly. The positive inotropic and chrontropic effect was observed in HLP of 6-hydroxydopamine-pretreated dogs and was abolished with propranolol. Labetalol produced a relaxation of the isolated trachea of the guinea pig, which was inhibited with propranolol. In doses higher than those required for alpha- and beta-adrenoceptor blockade, labetalol produced calcium-antagonistic action.

Adrenergic alpha-Antagonists↗
PubMed1978

In vitro analysis of Ca-antagonistic effects of prenylamine as mechanisms for its cardiac actions.

Ca-antagonistic properties of prenylamine were studied using isolated guinea-pig and canine cardiac preparations. Prenylamine is a weak Ca-antagonist compared to nifedipine, verapamil and diltiazem. Lower doses of prenylamine slightly increased the tension, but higher doses decreased the tension of both the guinea-pig and canine cardiac preparations. It decreased the tension while maintaining the action potential of the normal guinea-pig atrial preparation and decreased both the tension and Ca-action potential of the depolarized guinea-pig atrial preparation. Similar to antiarrhythmic agents, prenylamine also decreased the max dV/dt of the normal guinea-pig atrial action potential.

Action Potentials↗
PubMed1977

Immunoreactivities of alpha-amylase of humans and rats.

The immunoreactivities of amylase from human saliva and pancreatic juice and rat parotid and pancreas were investigated. Antisera were prepared in rabbits against each of the human and rat amylase. Human salivary and pancreatic amylases reacted similarly with the antibodies to both human salivary and pancreatic amylases. Rat parotid and pancreatic amylases reacted differently with the antibodies to both rat parotid and pancreatic amylases.

Amylases↗