The kinetics of blood pressure changes and plasma angiotensin converting enzyme (ACE) inhibition in response to ramipril (HOE 498), 10 mg orally, were studied in 6 nephrectomized subjects 12 hours after ultrafiltration and in 10 patients with essential hypertension. Ramipril lowered supine and standing blood pressure in both groups, but the effect was greater in essential hypertension. The maximal blood pressure response followed the effect on plasma ACE after a lag time of 3 to 4 hours in both groups. These data provide indirect evidence that ramipril lowers blood pressure, at least in part, independently of its effect on the circulating renin-angiotensin system, possibly by acting on tissue ACE.

Administration, Oral↗

PubMed1987

Effect of a single oral dose of milrinone on left ventricular diastolic performance in the failing human heart.

In 14 patients with severe congestive heart failure, left ventricular pressure (measured by tip manometer) and derived variables were measured before and every 10 minutes after administration of oral milrinone (10 mg) for 50 minutes along with measurements of coronary sinus blood flow and drug plasma levels. Arterial and coronary sinus catecholamines were measured only before and 50 minutes after milrinone. Left ventricular pressure, volume (as determined by angiography) and derived indexes were simultaneously assessed at matched atrial paced heart rate before and 60 minutes after milrinone. Three patients who did not achieve a therapeutic plasma level (less than 150 ng/ml) were excluded. Peak negative first derivative of left ventricular pressure (-dP/dt) progressively and significantly increased (10%) together with a decrease in the two exponential time constants of relaxation, namely, Tau 1 (19%) and Tau 2 (22%), which represent the fit for and after the first 40 ms, respectively. Coronary flow significantly increased by 43% within 30 minutes, whereas the decrease (-13%) in coronary vascular resistance failed to be statistically significant. No change occurred in catecholamine concentrations after milrinone. Peak filling rate significantly increased by 15%. Pressure-volume curves showed a leftward and, in four patients, a downward shift; a significant decrease in minimal left ventricular diastolic and end-diastolic pressures (by 55 and 38%, respectively) and in end-diastolic volume (18%) occurred. The constant of elastic chamber stiffness measured by the simple elastic model tended to decrease, but failed to achieve a statistically significant level. Thus, oral milrinone improved left ventricular early relaxation and filling as well as chamber distensibility. This global improvement of diastolic function makes milrinone a potentially useful drug in the oral treatment of heart failure.

Administration, Oral↗

PubMed1987

Who should be converted from cyclosporine to conventional immunosuppression in kidney transplantation, and why.

Twenty-three cadaveric renal allograft recipients with stable but compromised kidney function were electively converted from cyclosporine to azathioprine one year after transplantation. Within a few weeks glomerular filtration rate (GFR) rose by 40% and serum creatinine fell from 171 +/- 12 (mean +/- SEM) to 129 +/- 7 mumol/L. The increase in GFR was due to an increase in effective renal plasma flow of 21%. This suggests that one year of continuous cyclosporine (CsA) therapy does not result in irreversible structural renal damage. Although antihypertensive treatment was not changed, blood pressure fell from 142 +/- 4/90 +/- 3 to 123 +/- 3/77 +/- 2 mmHg. In addition a significant drop in serum cholesterol and triglycerides and an improvement in glucose tolerance were found. The beneficial effects on renal function, blood pressure, and metabolic indices were, however, outweighed by a high incidence of postconversion rejection in recipients of a second allograft. For these patients conversion from CsA to azathioprine seems therefore contraindicated. Recipients of a first kidney allograft can be converted safely, as long-term CsA administration in these patients induced a solid engraftment. The sequelae of the mode of treatment--impaired renal function, hypertension, and metabolic disturbances--are reversible even after late conversion.

Azathioprine↗

PubMed1987

Renal vein immunoreactive renin in patients with renal artery stenosis and essential hypertension.

In 36 patients with unilateral renal artery stenosis and in 24 with essential hypertension the plasma levels of total immunoreactive renin, and enzymatically active renin were measured in both renal veins (V) and in the aorta (A) by direct RIA by using monoclonal renin antibodies. Active renin and trypsin-activatable inactive renin were also measured by indirect RIA with angiotensin-I antibodies. The V/A ratio for the different forms of renin calculated from the results of direct and indirect RIA were not different. The V/A ratio of active renin for the kidney with the stenotic artery was 3.04 +/- 0.28 (mean +/- sem) with direct and 3.02 +/- 0.25 with indirect RIA. The contralateral ratio was 1.04 +/- 0.02 with the direct and 1.05 +/- 0.02 with the indirect RIA. In essential hypertension it was 1.28 +/- 0.04 with direct RIA and 1.28 +/- 0.04 with indirect RIA. Chronic treatment with captopril had no influence on this ratio in both patients groups. The V/A ratio of total immunoreactive renin was lower than that of active renin and this ratio had lost discriminative power for lateralization. This ratio was significantly greater than one on the affected side in renal artery stenosis but not contralaterally and in essential hypertension. This study shows that renin activity after trypsin-activation of plasma is an accurate measure of the total renin concentration, i.e. active renin plus prorenin. It also shows that a kidney with a stenotic artery secretes inactive renin, which is immunologically related to active renin and is likely to be prorenin. Direct RIA for measuring active renin is technically more simple than indirect RIA. Direct RIA however is somewhat less sensitive. For measuring the V/A ratio for active renin in patients with renal artery stenosis this can be overcome by stimulating the renin-angiotensin system for instance by captopril.

Antibodies, Monoclonal↗

PubMed1987

Role of alpha-adrenergic blockade in the cardiovascular actions of ketanserin: studies in patients with essential hypertension, autonomic insufficiency, and Raynaud's phenomenon.

It remains to be established whether ketanserin's antihypertensive effect is caused by S2-serotonergic blockade, by alpha 1-adrenergic blockade, or by a combination of both. Ketanserin, 10 mg i.v. or 40 mg t.i.d. orally, blocked the serotonin-induced contractions of hand veins in patients with essential hypertension. Intravenous ketanserin had no effect on the venoconstrictor action of noradrenaline. The increase in digital blood flow after i.v. ketanserin, as measured by the change in digital skin temperature in patients with Raynaud's phenomenon, was not blocked by phentolamine or pretreatment with prazosin. Intravenous ketanserin also lowered arterial pressure in patients with autonomic insufficiency who were unresponsive to phentolamine. These observations suggest that alpha-adrenergic blockade is not the sole mechanism of ketanserin's cardiovascular actions in humans.

Adrenergic alpha-Antagonists↗

PubMed1987

Mechanism of action of ketanserin in hypertension and vasospastic disease.

It remains to be established whether ketanserin's antihypertensive effect is caused by blockade of serotonergic type 2 receptors (S2), by blockade of alpha 1-adrenoceptors or by combined effect on both receptors. We therefore performed several clinical studies. Ketanserin, 10 mg i.v., lowered blood pressure in 6 patients with essential hypertension and blocked, at the same time, the contraction of hand veins to exogenous serotonin. In contrast, ketanserin had no effect on the venoconstrictor action of noradrenaline. Ketanserin also did not alter the pressor effect of bolus injections of the alpha 1-agonist phenylephrine. Furthermore, ketanserin had a distinct hypotensive effect in 4 normotensive patients with autonomic insufficiency who were unresponsive to alpha 1-adrenoceptor blockade. Moreover, the ketanserin-induced marked increase in digital blood flow in 7 patients with Raynaud's phenomenon was not blocked by pretreatment with high doses of the alpha 1-adrenoceptor blockade. However, in patients with essential hypertension, the antihypertensive effect of ketanserin was blunted by pretreatment with prazosin. This may be related to S2 blockade of the alleged amplifying effect of serotonin on alpha 1-adrenoceptor mediated vasoconstriction but the data do not exclude concomitant alpha-blockade by ketanserin. We conclude that the mechanism of ketanserin's antihypertensive effect requires further clarification; nevertheless the data cited above do not support the view that ketanserin is nothing more than another alpha-blocker.

Blood Pressure↗

PubMed1987