Search PubMed⌕ Search

Biomedical subjects

F Takenaka

Publications and source records attributed to F Takenaka.

At least 55 records · Page 3Linked to original sources
PubMed1975

[Effects of 5-(3-tert-butylamino-2-hydroxy) propoxy-3,4-dihydrocarbostyril hydrochloride(OPC-1085) on coronary circulation and myocardial metabolism].

Effects of a new beta-adrenergic blocking agent, 5-(3-tert-butylamino-2-hydroxy) propoxy-3,4-dihydrocarbostyril hydrochloride (OPC-1085), on the coronary circulation and myocardial metabolism were investigated in anesthetized open-chest dogs and isolated perfused dog hearts. In anesthetized open-chest dogs, OPC-1085 antagonized the responses to isoproterenol of heart rate, Vmax, mean blood pressure, myocardial oxygen consumption, coronary blood flow and redox potential. The antagonistic potency of OPC-1085 was stronger than propranolol. OPC-1085 3 to 30 mug/kg caused appreciable decreases, but in doses of 100 to 1,000 mug/kg caused increases in heart rate and Vmax. The effect of OPC-1085 on max dp/dt was similar to that on Vmax. However, propranolol 3 to 3,000 mu-g/kg caused only decreases in heart rate, Vmax and max dp/dt. OPC-1085 3,10 mu-g/kg while propranolol 30, 100 mu-g/kg caused a fall in myocardial oxygen consumption and coronary blood flow. In isolated perfused hearts, intracoronary injection of OPC-1085 0.1 mg almost completely suppressed isoproterenol-induced augmentation of heart rate, myocardial contractile force and coronary blood flow and reduction of redox potential. OPC-1085 0.1 mg caused slight increases in heart rate, myocardial contractile force and myocardial oxygen consumption. It is concluded that OPC-1085 is a more potent beta-adrenergic blocking agent than propranolol and possesses a weak negative inotropic effect in doses of 3 to 30 mu-g/kg and a intrinsic sympathomimetic activity in doses of 100 to 1,000 mu-g/kg.

Animals↗
PubMed1975

Effects of drugs and sympathetic nerve stimuation on retrograde coronary blood flow in dogs with experimental coronary occlusion.

Effects of nitroglycerin, dipyridamole, adenosine, reactive hyperemia, propranolol, norepinephrine and sympathetic nerve stimulation on retrograde coronary blood flow were investigated in dogs with experimental coronary occlusion. The retrograde blood flow (RF), pressure and conductance of the occluded left anterior descending coronary artery were measured and compared with the flow (CF), pressure and conductance of the non-occluded circumflex artery. The RF increased during sympathetic nerve stimulation and after the administration of nitroglycerin and norepinephrine, while it decreased during reactive hyperemia and following injection of dipyridamole, adenosine and propranolol. The RF/CF ratio was increased by nitroglycerin and propranolol, whereas it was lowered by dipyridamole and adenosine. The results suggest that nitroglycerin and propranolol may produce a redistribution of myocardial blood flow and that the collateral vessels are little influenced by sympathetic nerve stimulation.

Adenosine↗
PubMed1974

Afferent fibres from pulmonary arterial baroreceptors in the left cardiac sympathetic nerve of the cat.

1. Afferent discharges were recorded from the left cardiac sympathetic nerve or the third sympathetic ramus communicans of anaesthetized cats. Twenty-one single units with baroreceptor activity were obtained.2. The receptors of each unit were localized to the extrapulmonary part of the pulmonary artery, determined by direct mechanical probing of the wall of the pulmonary artery after death of the animals. Conduction velocity of the fibres ranged from 2.5 to 15.7 m/sec.3. Afferent discharges occurred irregularly under artificial ventilation. The impulse activity was increased when pulmonary arterial pressure was raised by an intravenous infusion of Locke solution, or by occlusion of lung roots, and decreased by bleeding the animal from the femoral artery.4. Above a threshold pressure, discharges occurred synchronously with the systolic pressure pulse in the pulmonary artery. A progressive further rise in pressure did not produce an increase in the number of impulses per heart beat. Occlusion of lung roots initially elicited a burst of discharges but the number of impulses for each cardiac cycle gradually decreased.5. The receptors responded to repetitive mechanical stimuli up to a frequency of 10/sec, but failed to respond to stimuli delivered at 20/sec.6. The results provide further evidence for the presence of afferent fibres in the cardiac sympathetic nerve. These afferent fibres are likely to provide the spinal cord with specific information only on transient changes in pulmonary arterial pressure.

Acetylcholine↗