[Central norepinephrine and angiotensin II contents in the brain regions of spontaneously hypertensive rats (SHR) and the interaction between them]

The norepinephrine (NE) and angiotensin II (A II) contents in the brain regions of SHR and WKY (Wistar Kyoto) rats at different ages were determined by fluorospectrophotometry and radioimmunoassay. The systolic blood pressure (SBP) of the rats was measured indirectly with a tail cuff technique in conscious state. The results were as follows: There was no significant difference in the central A II and NE contents between SHR and WKY rats at 8-week age. Since 12th week age the SBP of SHR has increased gradually, up to 16th to 20th week and then maintained steady level. Whereas there was no significant change of SBP in WKY rats in the same span of age. In the early and late states of hypertension the A II contents in the medulla oblongata, pons, hypothalamus and nucleus caudatus of SHR were markedly higher than those of the age-matched WKY rats. But the change of NE content of SHR in the early stage showed a different picture as compared with that of WKY rats, i.e., NE decreased in medulla oblongata and anterior hypothalamus but increased in pons, posterior hypothalamus and nucleus caudatus. However, in the late stage there was no such significant difference between SHR and WKY rats. Consequently, it is suggested that the central A II and NE participated in the development of hypertension of SHR, and that the maintenance of hypertension is mainly dependent upon the increased A II content. Microinjection of captopril or 6-OHDA in the lateral cerebroventricle of SHR elicited a decrease of BP and reduction of both A II and NE contents in the medulla and hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of the overactivated central renin-angiotensin system on the concentration of brain norepinephrine and epinephrine in stroke-prone spontaneously hypertensive rats and its significances]

The content of norepinephrine (NE) and epinephrine (E) in the brain of spontaneously hypertensive rats has proved abnormal, but the cause remained unknown. It was shown in the recent work that NE content in pons, posterior hypothalamus, nucleus caudatus and E concentration in medulla oblongata, anterior and posterior hypothalamus of 12-week old stroke-prone spontaneously hypertensive rats (SHRSP) were much higher than those of age-matched Wister-Kyoto rats (WKY). SHRSP also showed higher levels of systolic blood pressure (SBP) and brain angiotensin II (A II) than WKY. Intracerebroventricular (icv) perfusion of angiotensin-converting enzyme inhibitor captopril (20 micrograms for each time and three times for each day for four weeks) inhibited the synthesis of brain A II and reduced SBP and NE, E contents in all examined brain areas in SHRSP and WKY. However, the effects of chronically perfused captopril on SBP and brain NE, E levels in SHRSP were much more significant than in WKY. The results indicate that the modulatory effects of central renin-angiotensin system (RAS) on central adrenergic and noradrenergic system might be overactivated in SHRSP, which might partially responsible for the abnormally high levels of NE, E in some of the brain areas of SHRSP.

[Preliminary studies on the relationship between the blood pressure and renin-angiotensin system in brain and blood vessels in SHRSP]

This work analyzed the relationship between A I concentration in aorta tissue and systolic blood pressure (SBP) in stroke-prone spontaneously hypertensive rats (SHRSP) at different ages. The SBP of SHRSP increased progressively with the age until the age of 20 weeks, when the SBP of SHRSP no longer elevated but sustained at a relatively high and stable level. The A I concentration in aorta of SHRSP was much higher than that of Wistar Kyoto rats at all of the three different ages. Perfusion of captopril into the lateral cerebroventricle of SHRSP for four weeks evoked a considerable decrease of A I concentration in brain as well as a significant reduction of SBP accompanied by a decrement of A I concentration in aorta and concentration of norepinephrine and epinephrine in aorta tissue and plasma. The results further confirm the close relationship between the changed activity of renin-angiotensin system localized in blood vessels during hypertension and the pathogenesis of hypertension, and indicate the possible regulative control of A I generated from central nervous system over the production of A I from blood vessels by means of facilitating the activity of peripheral sympathetic nerve system.

Analysis of the causes of maternal death in China

Data were analysed on maternal mortality for 1984 in 287 cities, districts, and counties in 21 provinces, municipalities, and autonomous regions of China. The total population covered was 177.55 million, and during the study period there were 2 483 269 live births and 1211 maternal deaths, corresponding to a maternal mortality rate of 48.8 per 100 000. The main cause of maternal death was obstetric haemorrhage, followed, in order, by cardiac diseases, toxaemia of pregnancy, hepatic disease, puerperal infection, and amniotic fluid embolism. The health care measures received by the mothers who died are analysed, and methods of reducing the maternal mortality rate are proposed.