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[Hemodynamic and biological effects of bromocriptine in essential hypertension]
Insights
Bromocriptine (Br) effectively lowered blood pressure in patients with essential hypertension, correlating with a significant drop in prolactin levels. This suggests a central dopaminergic mechanism in hypertension treatment.
Area of Science:
- Cardiovascular Medicine
- Neuropharmacology
- Endocrinology
Context:
- Essential hypertension is hypothesized to involve central dopaminergic dysfunction.
- Agonist dopaminergic substances (AD) have demonstrated anti-hypertensive effects.
- Investigating novel therapeutic targets for hypertension is crucial.
Purpose:
- To evaluate the cardiovascular effects of a single oral dose of Bromocriptine (Br) in untreated essential hypertension patients.
- To assess the relationship between Bromocriptine's hemodynamic actions and biological parameters like plasma renin activity and prolactin levels.
- To explore the potential role of central dopaminergic pathways in essential hypertension.
Summary:
- A single 10 mg oral dose of Bromocriptine (Br) demonstrated a significant and prolonged anti-hypertensive action in essential hypertension patients.
- Bromocriptine induced a marked decrease in blood pressure, systemic arterial resistance, and pulmonary arterial pressure, with a notable correlation to prolactin level reduction.
- Changes in plasma renin activity and hemodynamic effects were consistent with central dopaminergic modulation, supporting the hypothesis of dopaminergic dysfunction in essential hypertension.
Impact:
- The findings support Bromocriptine as a potential therapeutic agent for essential hypertension, particularly if linked to dopaminergic dysfunction.
- This study provides evidence for the involvement of central dopaminergic pathways in the pathophysiology of essential hypertension.
- The strong correlation between blood pressure and prolactin levels suggests prolactin as a potential biomarker for assessing dopaminergic activity in hypertension.
Abstract:
Central dopaminergic dysfunction has been suggested as the cause of essential hypertension. Agonist dopaminergic substances (AD) possess documented anti-hypertensive properties. We studied the cardiovascular effects of a single oral dose of 10 mg of Bromocriptine (Br) in untreated subjects with essential hypertension. A number of hemodynamic and biological parameters (direct blood pressure, pulmonary arterial and capillary pressures, cardiac index, heart rate, right ventricular and left ventricular work indices, systemic arterial and pulmonary vascular resistance, plasma renin activity, prolactin, and circulating Br levels) were measured before and after ingestion of the drug (at I, 1,5, 2, 3, 4, 5, 6, 8, 10 and 12 hours). Despite great individual variability, under the experimental conditions, Br displayed a strong anti-hypertensive action. The fall in blood pressure was early (Ist our) progressive, stabilising between the 3rd and 6th hour and prolonged (12 hour). This response was independent of the basal blood pressure with basal plasma renin activity (R = 0.64; p less than 0.05) but not with the prolactin level. The left ventricular work index underwent a similar change. Systemic arterial resistance fell, but this occurred after the fall in blood pressure. There was an independent and significant fall in pulmonary arterial pressure and pulmonary vascular resistance. The prolactin level fell very quickly and remained low throughout the 12 hours. There was an excellent correlation between the direct blood pressure and prolactin level (r = 0.97; p less than 0.01). Plasma renin activity rose after the third hour to reach a maximum at the 8th hour. There was a weak correlation between the blood pressure and plasma renin activity (r = 0.65, p less than 0.05). The serum Br level varied from patient to patient but reached a maximum at 1 hour, remaining stable until the 6th hour before decreasing. There was a correlation between the plasma renin activity and prolactin levels at each dosage (r = 0.66; p less than 0.005). The hemodynamic effects of Br are similar to those of central anti-hypertensive agents. The changes in plasma renin activity are comparable to those observed in central dopaminergic dysfunction. The excellent chronological correlation between the change in blood pressure and prolactin level is compatible with the hypothesis of this type of dysfunction in essential hypertension, if the inhibition of prolactin is accepted as a central dopaminergic effect of bromocriptine.