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Biomedical subjects

T M Macdonald

Publications and source records attributed to T M Macdonald.

5 recordsLinked to original sources

Left ventricular diastolic dysfunction.

Diastolic heart failure is common, particularly in patients with coronary artery disease and hypertension. Although it does not contribute to heart failure mortality to the same degree as systolic dysfunction, it is responsible for significant morbidity. Clinical suspicion is a prerequisite to the diagnosis, which should be considered in all patients with exercise intolerance due to dyspnoea, particularly if associated with a history of ischaemic heart disease or hypertension. Although invasive haemodynamic studies are the gold standard investigation, this method of assessment is limited to a very small proportion of these patients, and echocardiography remains the single most useful investigation. It is important to realize that the management of diastolic heart disease depends to a large extent on the aetiology, which contrasts with the treatment of systolic dysfunction. As indicated, a wide variety of different drugs may potentially be of benefit, although considerable further research will be needed to more clearly define this heterogenous condition and its optimal treatment.

Diastole

The effect of lithium on the renal response to the dopamine prodrug gludopa in normal man.

1. The effect of oral lithium on the renal response to gamma-L-glutamyl-L-dopa (gludopa, 25 micrograms kg-1 min-1) was investigated in seven normal males. 2. Gludopa at this dose produced an 800-fold increase in urine dopamine excretion. It was natriuretic and suppressed plasma renin activity without altering blood pressure and pulse. 3. Lithium alone increased sodium excretion and stimulated plasma renin activity. However, it abolished the natriuresis produced by gludopa. 4. Gludopa did not significantly affect lithium clearance. 5. This study suggests that lithium interacts with dopamine at the proximal tubule and that the lithium clearance method is not suitable for investigating dopaminergic mechanisms in the kidney.

Adult

The effect of intravenous frusemide on urine dopamine in normal volunteers: studies with indomethacin and carbidopa.

1. The urine dopamine response to intravenous frusemide (30 mg) was investigated in 15 salt replete male volunteers. The effects of oral indomethacin (100 mg) and oral carbidopa (100 mg) given before intravenous frusemide were studied in the same group of subjects. 2. Frusemide produced a significant increase in urine dopamine output within 15 min. 3. Indomethacin attenuated the natriuretic and renin responses to frusemide, but did not alter urine dopamine output. 4. Carbidopa lowered urine dopamine to undetectable levels, but did not significantly affect the natriuretic and renin responses to frusemide. 5. We conclude that urine dopamine excretion after frusemide is not directly related to increased sodium excretion or renin response and it is not mediated by the prostaglandins. In addition, dopamine does not contribute to the renal actions of frusemide under normal conditions.

Administration, Oral

Psittacosis.

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Humans