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Biomedical subjects

I Gretzer

Publications and source records attributed to I Gretzer.

6 recordsLinked to original sources
PubMed1997

Differences between the effects of metoprolol and prazosin on the forearm vasculature in primary hypertension.

OBJECTIVES: To study the forearm vascular resistance in patients at rest and during ischaemia and cardiovascular responses to noradrenaline infusions during treatment with a beta1-adrenoceptor antagonist, metoprolol, and with an alpha1-adrenoceptor antagonist, prazosin. PATIENTS: Eighteen previously untreated primary hypertension patients were selected for therapy either with 50-250 mg/day metoprolol (n = 11) or with 3-20 mg/day prazosin (n = 8). METHODS: The minimal vascular resistance after ischaemic work was calculated from the forearm blood flow determined by venous occlusion plethysmography before treatment and after two and 16 months of treatment Arterial and venous plasma noradrenaline levels were determined and systemic pressor responses and forearm vasoconstriction were studied during intravenous infusion of noradrenaline. RESULTS: The resting mean arterial pressure was reduced differently by metoprolol and prazosin (by 20% versus by 8%; P < 0.001 for difference). The minimal vascular resistance decreased similarly after 16 months of metoprolol (17% decrease; P < 0.05) and of prazosin (24% decrease; P < 0.05) treatments. Arterial noradrenaline levels increased after 16 months of metoprolol treatment and after 2 and 16 months of prazosin treatment. The forearm noradrenaline spillover was reduced after 16 months on prazosin, but remained unchanged during metoprolol treatment. Pressor responses to intravenous noradrenaline were affected little by either treatment, whereas reflexogenic bradycardia was attenuated by prazosin treatment. CONCLUSION: The findings suggest that metoprolol and prazosin treatments reduce the minimal vascular resistance similarly, despite different reductions in blood pressure. Prazosin treatment might also reduce the forearm sympathetic nerve activity. Reductions in minimal forearm vascular resistance during antihypertensive therapy need not be related only to the lowering of the blood pressure per se.

Adrenergic alpha-Antagonists↗
PubMed1995

Computerized evaluation of the peripheral blood flow during maximal vasodilatation in humans using venous occlusion plethysmography.

Forearm blood flow was studied with venous occlusion plethysmography after ischaemic exercise in 10 healthy volunteers and 10 hypertensive patients. The peak blood flow was calculated by three methods: the manual conventional graphic technique and by fitting of a tangent to the inflow curve with the help of a computer. In addition a computer-aided derivation of an exponential curve adapted to the initial part of the inflow curve was used for the calculation of the maximal blood flow. With the two tangential techniques the peak mean blood flow values did not differ significantly and were 58 ml min-1 100 ml-1 tissue while the exponential derivation procedure gave in both groups about 40% higher maximal flow values. The effect of venous occlusion on the linear velocity of the brachial arterial blood flow blood was studied with Ultrasound Doppler Flowmetry. The maximal flow velocity after ischaemic exercise decreased by about 18% during 50 mmHg venous occlusion; the influence of the venous stasis was least during the first heart beats after the onset of the venous occlusion. The effect of the venous stasis was similar but less pronounced in the hypertensive patients. In conclusion, forearm blood flow during maximal vasodilatation is reduced by venous occlusion and the best estimate of the flow is obtained from the earliest part of the venous occlusion inflow curve, as indicated by the use of the computer-aided exponential derivation technique.

Adult↗
PubMed1986

Beta-blocking effect and pharmacokinetics of pindolol in young and elderly hypertensive patients.

The pharmacokinetics and beta-blocking effect of pindolol has been compared in 20 patients with essential hypertension (WHO Stage I), 10 below 25 years of age and 10 older than 60 years. Each patient received pindolol 10 mg p.o. once a day for 5 days. The area under the curve (AUC) of pindolol was larger in the old than in the young patients both on the first (p less than 0.05) and the fifth (p less than 0.01) days. The AUC of pindolol was 14% higher on the fifth day compared to the first day in the elderly group, indicating minor accumulation at steady-state. There was no change in AUC in the young patients. Endogenous creatinine clearance was lower in the old (80 +/- 9 ml/min) than in the young patients (150 +/- 45 ml/min). The beta-blocking effect did not differ between the groups at 2 h after administration of pindolol on Days 1 or 5. However, 24 h after the first and fifth doses approximately 60% of the beta-blockade persisted in the old group whereas 17 and 19% of the beta-blockade, respectively, persisted in the young group; the difference between the groups was statistically significant (p less than 0.01). The most probable explanation for the more sustained beta-blocking effect in the elderly is the physiologically decrease in renal function, which results in a more sustained plasma level of pindolol in those patients.

Adrenergic beta-Antagonists↗
PubMed1986

Long-term effects of pindolol on serum lipoproteins in hypertensive patients.

Serum lipoproteins were analysed in 11 hypertensive patients before and after 2 and 16 months on pindolol therapy. In all patients significant blood pressure reductions were achieved with a mean pindolol dose of 13 mg (range 5-30) per day at 16 months' follow-up. After 2 months a significant increase by 35% was found in VLDL TG and cholesterol concentrations, but after 16 months all lipoprotein values had reverted to pretreatment levels. HDL did not change during pindolol therapy. It is not established whether the lack of long-term effects of pindolol on serum lipoprotein is specifically due to its high degree of intrinsic sympatomimetic activity.

Adult↗
PubMed1985

Haemodynamic effects of pindolol in essential hypertension with special reference to resistance vessels in the forearm during maximal vasodilatation.

Eleven patients, mean age 45 years, with previously untreated hypertension (WHO stage I) were treated over 16 months with pindolol in dosages of 5-30 mg/day. The effects on blood pressure and peripheral vascular resistance (PR) were studied before and after 2 and 16 months of treatment. Recordings were performed at rest, and after maximal vasodilatation obtained by ischaemic work to exhaustion with a hand-ergometer. Blood pressure was significantly reduced after both 2 and 16 months of treatment (P < 0.001). During treatment small reductions in heart rate were seen at rest but not after maximal vasodilatation (P < 0.02 and NS, respectively). At rest there was a great variability and no significant changes in PR. Peripheral vascular resistance after maximal vasodilatation was significantly reduced after both 2 and 16 months of treatment (P < 0.005 and P < 0.01, respectively). We conclude that long-term treatment with pindolol may give a regression of structural vascular changes.

Adult↗