Increased nitric oxide activity in early renovascular hypertension

A decreased influence of nitric oxide (NO) in the peripheral vasculature is associated with the pathophysiology of established hypertension, and some studies suggest that increased blood pressure positively correlates with decreased NO production. If so, then the increased arterial pressure in one-kidney, one-clip (1K1C) hypertensive rats should be associated with decreased circulating levels of nitrite/nitrate (NO2/NO3; stable metabolites of NO) and guanosine 3',5'-cyclic monophosphate (cGMP; mediator of NO action). We measured serum NO2/NO3 and cGMP levels in early hypertensive 1K1C (2 wk after clipping) and shamoperated one-kidney (1K) normotensive rats, treated orally with or without the NO-synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 2 wk). Compared with those in 1K rats, NO2/NO3 and cGMP levels were increased in 1K1C hypertensive rats but not in 1K1C rats treated with L-NAME. NO2/NO3 and cGMP levels in L-NAME-treated 1K and 1K1C rats were similar. Compared with that in 1K rats, systolic blood pressure (SBP) was increased in 1K1C rats and in L-NAME-treated 1K and 1K1C rats. The SBP increase in L-NAME-treated 1K1C rats was more rapid than in untreated 1K1C rats. In early hypertension, increases in SBP positively correlated with increases in serum NO2/NO3 and cGMP. After 2 wk of hypertension, circulating NO2/NO3 levels gradually declined and reached prehypertension levels by the fifth week of hypertension. These results provide evidence for increased NO synthesis in early hypertensive 1K1C rats, and this increased NO could be a compensatory mechanism to slow the development of hypertension in these animals.

Humoral factors trophic for vascular smooth muscle during the development of hypertension in rats

There is evidence that a humoral factor or factors in rats with one-kidney, one-clip (1K1C) hypertension increase growth of cultured vascular smooth muscle cells. Such humoral trophic factors may contribute to the abnormal growth of arterial muscle in hypertension. To further study the longitudinal expression of this trophic factor or factors, we prepared rats with 1K1C hypertension of different durations. To determine if the factor or factors are also expressed in other forms of experimental hypertension, we additionally prepared rats with two-kidney, one-clip (2K1C) hypertension and paired two-kidney (2K) normotensive controls; we also studied Spontaneously Hypertensive Rats (SHR) plus appropriate controls. In the presence of growth stimulated by background levels (1%) of fetal calf serum, 20% platelet-poor, plasma-derived serum (PDS) from 1K1C rats 8-14 days (n = 10) and 28 days (n = 12) after clipping increased [3H]-thymidine incorporation of growth-arrested cultured rat aortic smooth muscle cells more than the paired 1K PDS, by up to +67% and +40%, respectively (P < 0.01). However, with PDS from 1K1C rats 4 days (n = 11) and 38 days (n = 6) after clipping there was no evidence for a differential effect (P > 0.5 and P > 0.1, respectively). PDS from seven 2K1C rats (at 9 days) also increased [3H]-thymidine incorporation of the assay cells more than PDS from the paired 2K rats, by up to +19% (P < 0.05). However, there was no evidence that PDS from SHR differentially increased cellular thymidine incorporation. Thus, evidence from this study suggests that the humoral factor or factors trophic for vascular smooth muscle are expressed in both low- and high-renin forms of experimental renovascular hypertension, but not in the very early or in the late complicated stages of the hypertension, or in genetic hypertension in rats.

Household distribution of contraceptives in rural Egypt

Oral contraceptives were offered to all married, fecund women 15-44 years of age living in 38 Egyptian villages with a population of 200,000. Before the household distribution, contraceptive prevalence was 19.1 percent. Nine months after the distribution, the contraceptive prevalence increased to 27.7 percent, a relative increase of 45 percent. Based on this study, a modified delivery system is currently being tested on a governoratewide basis. The modified system will include a wider range of fertility regulation methods and will also have health and community development components.