Experimental and clinical approaches to treatment of hypertension by dopamine receptor agonists

The action of several dopamine agonists on blood pressure was investigated. In dogs, apomorphine induced a decrease in blood pressure and an increase in heart rate. These effects were suppressed by intravenous haloperidol or phentolamine. Intravenous but not intracisternal domperidone suppressed the hypotensive responses elicited by intravenous or intracisternal apomorphine. Furthermore, the hypotensive effect of bromocriptine or apomorphine was abolished in adrenal demedullated dogs. Apomorphine and bromocriptine decreased adrenal catecholamine levels. In men, the acute hypotensive property of apomorphine (but not the long term effect of bromocriptine) was suppressed by pretreatment with domperidone. In hypertensive Parkinsonians, bromocriptine reduced blood pressure, induced an increase in inulin clearance, a decrease in plasma creatinine concentration and in renal vascular resistances. These results suggest that dopamine agonists (like apomorphine or bromocriptine) reduce blood pressure through both a decrease in sympathetic tone and an improvement in renal function. However, the mechanism of the acute and long term hypotensive effects could be different only involving peripheral mechanisms after acute administration and both peripheral and central structure under chronic treatment. In addition, preliminary results suggesting the potential interest of dopamine antagonists in the management of orthostatic hypotension are discussed.

Parkinson's disease and hypertension: chronic bromocriptine treatment

We studied the effects of bromocriptine therapy (mean dosage, 56.0 mg daily) for 12 months in five patients with both Parkinson's disease and hypertension. Therapy improved neurologic manifestations and reduced both supine and standing systolic blood pressures and standing diastolic blood pressure with no consistent change in heart rate. Transient episodes of orthostatic hypotension appeared in two cases. Domperidone (60 mg daily for 1 month) did not abolish the antihypertensive effect of bromocriptine, suggesting that central dopaminergic or alpha-adrenolytic mechanisms are involved in this effect. Bromocriptine may be useful in the treatment of hypertension in patients with Parkinson's disease.

[How do we explain the antihypertensive effect of bromocriptine? Clinical and experimental contribution]

The mechanism of the antihypertensive properties of bromocriptine was investigated in dog and man. In anaesthetized dogs, bromocriptine induced a decrease in the pressor responses to adrenaline or phenylephrine and reduced the hypotensive properties of clonidine. In 6 hypertensive patients with Parkinson's disease, chronic treatment with bromocriptine (46.4 +/- 12.0 mg/day) elicited both a significant decrease in blood pressure and an improvement of extrapyramidal symptoms. During bromocriptine therapy, domperidone (60 mg/day during 1 month), a specific peripheral dopaminergic antagonist was introduced. The drug did not change the levels of blood pressure (before domperidone: 150.8 +/- 22.5/79.9 +/- 8.9 mmHg after domperidone: 150 +/- 17.3/87.5 +/- 12.9 mmHg). These results confirm the antihypertensive properties of bromocriptine and demonstrate that, beside their dopaminergic properties, the drug also possesses mixed alpha 1 and alpha 2 adrenolytic actions. These two properties may contribute to the mechanism of the antihypertensive effects of bromocriptine. These data also show that domperidone can be used in bromocriptine-treated hypertensive parkinsonians without side effects on blood pressure.

[Treatment of deep venous thrombosis in the presence of a congenital antithrombin III deficiency. Apropos of the use of purified concentrates]

The authors report the case of an active 32 year old man who developed right leg DVT. Before heparinisation, he was discovered to have a low antithrombin III level (biological activity (B) 60%, immunological level (I) 50) and a further inquiry showed the same abnormality in 4 members of the family, leading to a diagnosis of a congenital deficit: a 35 year old sister with a bilateral post-DVT changes had antithrombin III levels of 70% (B) and 45% (I); two nephews, sons of the affected sister: the one aged 5 years was asymptomatic despite antithrombin III levels of 50% (I) and 70% (B); the other had experience DVT at the age of 2 and, on oral anti-vitamin K drugs, had antithrombin III levels of 55% (I) and 67% (B) at the age of 15 years; the patient's brother died at the age of 29 of cerebral vein thrombosis after pulmonary embolism. The recurrence of local signs of DVT after 12 day's heparin therapy with AT III levels (B) of 40%, led to a change in management with infusion of purified AT III concentrate at a dose of 40 U per kg (2 500 U per hour). This induced a rise in AT III activity to over 100% and enabled early introduction of anti-vitamin K therapy. The patient remains asymptomatic after 6 months follow-up. This case illustrates the value of determining AT III activity in all patients who developed DVT without obvious reason.(ABSTRACT TRUNCATED AT 250 WORDS)

[Corynebacterium (JK group) endocarditis. Apropos of a case]

The authors report a case of Corynebacterium (group JK) endocarditis. The main characteristics of the causative pathogen are specified: diagnostic bacteriological criteria, pathogenic capability after cardiac surgery, therapeutic problems related to resistance to antibiotics.

[Role of the TRF test in the study of atrial dysrhythmia]

The aim of this retrospective study of 43 patients (32 females) aged 26 to 84 years old (mean 62 +/- 14,5) was to assess the value of the TRF test in cases with normal static endocrine levels and isolated arrhythmias: 25 atrial fibrillations, 3 atrial flutters, 10 sinus tachycardias, 2 junctional tachycardias, 2 focal atrial tachycardias and 1 atrial extrasystoles. There was underlying cardiac disease in 24 patients. Thyroid function was assessed by T4, T3 and the TRF test. There was no relationship between cardiac disease and arrhythmias with the levels of TSH 25 minutes after TRF. The reactivity to TRF was low: 5,8 +/- 5,6 microU/ml. Nineteen patients were hyperthyroid (TSH at O and 25 min: 1,7 +/- 0,5 and 2 +/- 1 microU/ml respectively), in the following three eventualities: - Clinical hyperthyroidism and raised hormonal levels, the TRF confirmed the diagnosis in 10 out of 11 cases; - Clinical hyperthyroidism and normal hormone levels: the TRF confirmed the diagnosis in 8 out of 14 cases; - Normal clinical examination and normal hormone levels: the TRF test showed a hyperthyroid reaction in 1 out of 18 cases. T3 and T4 measurements are often misleading. The TRF test with 2 blood samples would appear to be essential, especially in patients over 60 years of age. The hyperthyroid population was older (68,5 +/- 8 years) and the mean values of the thyroid investigations (T3, T4 and STH at 25 minutes) were significant. Underlying cardiac disease was detected in over half these cases. Atrial fibrillation was the commonest arrhythmia. Each case of arrhythmia, whether or not related to hyperthyroidism, justifies echocardiography.

[A study of antithrombin systems during heparin therapy]

Plasma levels of three thrombin inhibitors (antithrombin III--AT-III-, alpha 2 macroglobulin - alpha 2M -; alpha 1 antitrypsin - alpha 1 AT-) were measured, together with total plasma antithrombin activity (Howie's method), in 19 hospital patients with venous thromboembolic disease before and during heparin therapy. A decrease in AT III levels was observed during treatment and found to correlate significantly with heparin plasma levels, but there were no significant changes in alpha 2M and alpha 1 AT levels. Variations in total plasma antithrombin activity were not significant. In 9 patients whose AT III levels were under 60% a significant increase in alpha 2M level was noted. The therapeutic problems associated with this category of patients are discussed.