Outcome of Pregnancy in an Oxford-Cardiff Cohort of Women with Previous Bacteriuria

To investigate the influence of asymptomatic bacteriuria inchildhood on subsequent pregnancy, we reviewed the outcome of139 pregnancies in 88 women who were first identified duringa programme of screening schoolgirls for asymptomatic bacteriuriacarried out between 1970–1972 [1]. Data were analysedfor the following groups: 50 pregnancies in 28 women with knownrenal scars (group 1); 16 pregnancies in 14 women with normalkidneys and reflux (group 2); 73 pregnancies in 46 women withnormal urinary tracts (group 3); 139 healthy controls. Women in group 1 had a 3.3-fold increased relative risk of hypertension(p < 0.01) and a 7.6-fold increased risk of pre-eclampsia(p< 0.05) compared to controls, and a higher rate of obstetricinterventions, including emergency caesarean section. Womenin groups 2 and 3 appeared to carry a slightly increased riskof hypertension during the last trimester (RR = 1.8) but therewere no significant differences in this or the incidence ofpre-eclampsia or mode of delivery. Bacteriuria was more prevalentin all index groups compared to controls (37 per cent vs. 8per cent, p < 0.01) and included four cases of acute pyelonephritisin the study group. Fetal outcome was satisfactory in all cases.These results suggest that women with renal scars are at riskof hypertension and pre-eclampsia during pregnancy but thatmodern obstetric care minimizes these risks.     

Cardiovascular and endocrine effects of a single course of maternal dexamethasone treatment in preterm fetal sheep

OBJECTIVE: To determine the effects of a single course of maternally administered dexamethasone on preterm fetal sheep in utero. DESIGN: Prospective randomised controlled trial. SETTING: University laboratory. SAMPLE: Pregnant sheep at 0.7 of gestation. METHODS: Pregnant ewes at 103 days of pregnancy (term = 147 days) were given two intramuscular injections of vehicle (n= 7) or 12 mg of dexamethasone (DEX; n= 8) 24 hours apart. Fetuses were continuously monitored for five days. MAIN OUTCOME MEASURES: Fetal mean arterial blood pressure, carotid and femoral arterial blood flow and vascular resistance, heart rate, heart rate variability, fetal plasma cortisol and ACTH and fetal body movements. RESULTS: DEX injections led to an acute increase in mean arterial blood pressure with a rise in carotid and femoral vascular resistance, a fall in femoral arterial blood flow, and a brief fall in fetal heart rate followed by significant tachycardia. From 24 hours after the injections, mean arterial blood pressure and vascular resistance returned to control values, however, a mild tachycardia [200 (3) vs 184 (4) bpm, P < 0.05] and loss of the circadian pattern of fetal heart rate variability persisted until the end of recording. Plasma ACTH and cortisol were markedly suppressed by DEX (P < 0.05), with values returning to control levels 32 and 72 hours after the first injection, respectively. There was no effect on basal fetal heart rate variability, body movements, carotid arterial blood flow, or the circadian pattern of fetal heart rate. CONCLUSION: In contrast to previous experiments utilising direct fetal infusion of steroids, maternal administration of DEX was associated with only transient hypertension.     

Effects of chronic sympatho-inhibition on reflex control of renal blood flow and plasma renin activity in renovascular hypertension

Background and purpose:

We determined if chronic sympatho-inhibition with rilmenidine has functional significance for the kidney by altering responses of renal blood flow (RBF) and plasma renin activity (PRA) to stress and acute hypotension in rabbits with renovascular hypertension.

Experimental approach:

RBF to each kidney and renal sympathetic nerve activity (RSNA) to the left kidney were measured in rabbits in which a renal artery clip induced hypertension (2K1C) and in sham-operated rabbits. After 2 weeks, a subcutaneous minipump was implanted to deliver rilmenidine (2.5 mg·kg⁻¹·day⁻¹) to 2K1C rabbits for 3 weeks.

Key results:

After 5 weeks of renal artery stenosis, mean arterial pressure (MAP) was 23% higher and PRA 3-fold greater than in sham-operated rabbits. Blood flow and renal vascular conductance in the stenosed kidney were lower (−75% and −80%) compared with sham, and higher in the non-clipped kidney (68% and 39%). Responses of RBF and PRA to hypotension were similar in 2K1C and sham rabbits. Airjet stress evoked a greater increase in MAP in 2K1C rabbits than sham controls. Chronic rilmenidine normalized MAP, reduced RSNA and PRA, and did not reduce RBF in the stenosed kidney. Responses of RBF (clipped and non-clipped kidney), RSNA and PRA to hypotension and airjet were little affected by rilmenidine.

Conclusions and implications:

Our observations suggest that chronic sympatho-inhibition is an effective antihypertensive therapy in renovascular hypertension. It normalizes MAP and reduces basal PRA without compromising blood flow in the stenosed kidney or altering responses of MAP, haemodynamics and PRA to acute hypotension and stress.