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Biomedical subjects

M F Oliver

Publications and source records attributed to M F Oliver.

248 records · Page 14Linked to original sources
PubMedDate not supplied

Alpha-adrenoceptor control of norepinephrine release from acutely ischaemic myocardium: effects of blood flow, arrhythmias, and regional conduction delay.

We studied the effects of yohimbine, and alpha-adrenoceptor blocker with selectivity for the alpha 2-subtype, on myocardial norepinephrine (NE) overflow, regional myocardial blood flow (RMBF), and patterns of epicardial conduction abnormalities during occlusion of the proximal left anterior coronary artery in an open-chest anaesthetised dog model. With a 12-min period of coronary occlusion (n = 9), spontaneous overflow of NE into ischaemic venous effluent was not observed either before or after yohimbine (1 mg/kg i.v.), but the drug significantly potentiated the enhanced NE overflow during supramaximal stimulation of the left stellate ganglion at low (1 Hz) and high (10 Hz) frequency [peak NE 4.3 +/- 0.4 pmol/ml control; 11.8 +/- 5.4 pmol/ml yohimbine (p less than 0.005)] with a delayed return towards prestimulation levels. Myocardial NE overflow on coronary reperfusion was also enhanced. Yohimbine increased arterial epinephrine two- to threefold but did not substantially alter myocardial lactate overflow during coronary occlusion. RMBF was reduced 24 and 36% to ischaemic endocardium and epicardium, respectively (p less than 0.01, compared with control occlusion). This contrasted with a 9 and 6% decrease in flow to the respective nonischaemic areas (p = NS, compared with control occlusion. Spontaneous ventricular fibrillation and the area and magnitude of epicardial conduction abnormalities in the ischaemic myocardium were both increased compared with the control occlusion. Thus, alpha-blockers with selectivity for the alpha 2-adrenoceptor may be detrimental to acutely ischaemic myocardium, presumably through increased local catecholamine release at the nerve terminal.

Animals↗
PubMedDate not supplied

Electrophysiological and haemodynamic effects of a new inotropic agent (UK14275) in the dog.

1. Electrophysiological and haemodynamic effects after intravenous administration of a new inotropic agent (UK14275) have been examined in open-chest dogs under pentobarbitone anaesthesia. 2. UK14275 produced slight shortening of QT interval, ventricular functional refractory period and atrio-ventricular conduction time but did not affect action potential duration or endocardial-epicardial conduction time. 3. Cardiac output and left ventricular dP/dt increased, and systemic vascular resistance fell. 4. An end-systolic pressure gradient developed between left ventricle and aorta attributable to left ventricular cavity obliteration.

Animals↗
PubMedDate not supplied

Lowering cholesterol in old age.

In arguing for a conservative view of the need for and wisdom of lowering plasma cholesterol, or low density lipoprotein cholesterol, in advanced age, three considerations are taken into account. These are: plasma cholesterol concentrations decrease spontaneously with age, as does their association with vascular disease; the absence of data to demonstrate the benefits of lowering cholesterol levels in the elderly; and conflicting priorities (including the cost of treatment) in the care of the elderly. Patients with known coronary heart disease who have received lipid-lowering treatment for some years could continue to be treated with these drugs beyond the age of 75, though even this decision should depend on clinical judgement.

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