Effects of nifedipine and nicardipine on regional cerebral blood flow distribution in patients with arterial hypertension.

Regional cerebral blood flow (rCBF) in 75 patients with arterial hypertension and symptoms of chronic ischemic cerebrovascular disorders was studied by using the 133Xenon infusion technique and a 30-detector setup. A baseline decrease in the mean hemispheric blood flow (rCBFh) with elevated deviations of rCBF from rCBFh were observed in the hemispheres. A single oral dose of either nifedipine or nicardipine induced various changes in rCBF. The drug effects regarding changes in the mean value of the hemispheric blood flow and the flow distribution were classified into 4 types. A decrease in the deviation of rCBF from the hemispheric mean CBF accompanied by an increase in the total brain blood flow was considered to be the most beneficial drug effect. This positive reaction was found more frequently when patients were given nicardipine. In some patients both drugs induced nonbeneficial changes in rCBF with an increase in the number of ischemic and hyperemic regions. It was hypothesized that such variants of drug effects may result in the deterioration of brain perfusion, contributing to development of focal brain ischemic damages. The effects of drugs were similar after both single doses and 2-week monotherapy. It is suggested that the analysis of drug effects on regional CBF distribution may be useful for estimating clinical importance of changes in cerebral hemodynamics during antihypertensive therapy.

[The characteristics of the cerebral circulation in arterial hypertension]. / Osobennosti tserebral'noi tsirkuliatsii pri arterial'noi gipertenzii.

In arterial hypertension, cerebral blood flow (CBF) in patients with chronic cerebrovascular diseases is lower than in patients without hypertension. In stenosis of internal carotid arteries, hypertension leads to the disturbance of the response of resisting cerebral vessels compensating the decrease of perfusion pressure at the expense of vessel dilation. As compared with patients without hypertension, the difference between the values of regional CBF (rCBF) in various regions of the brain is more obvious with the appearance of alternate hypoemic and hyperemic regions. After nifedipine, both an increase and a decrease of hemispheric CBF is possible in these patients. In many of them such changes in CBF are combined with further increase of the difference between rCBF values in various parts of the brain with the formation of well marked zones with relative ischemia and hyperemia.

[Status of the prostacyclin-thromboxane balance in patients with cerebrovascular disorders and the effect of the treatment with nifedipine]. / Sostoianie prostatsiklin-tromboksanovogo balansa u bol'nykh s narusheniiami mozgovogo krovoobrashcheniia i vliianie na nego terapii nifedipinom.

It is shown that in patients with cerebral circulatory disorders, the prostacyclin -thromboxane balance is replaced toward the latter one. As a result of nifedipine administration part of the test subjects demonstrate a rise of the content of prostacyclin and a decline of the concentration of thromboxane. This effect of nifedipine is ascertained to be in a good agreement with its action on blood inflow to the brain and platelet aggregation. It is concluded that the efficacy of nifedipine can be raised if it is combined with the drugs that enhance the synthesis of prostacyclins in the body.