Raised prorenin and renin concentrations in pre-eclamptic placentae when measured after acid activation.

Aim: The aim of the study was to ascertain if there was any difference in the levels of prorenin and active renin between pre-eclamptic and normotensive feto-placental tissues.

Methods: Supernatants of homogenates from fresh, vaginally delivered placentae from 15 normotensive and 15 pre-eclamptic women were measured for renin concentration (RC), prorenin concentration and renin activity (RA). RA and RC were measured in the absence and presence of nephrectomised sheep plasma, respectively. Prorenin was estimated as the difference between renin concentration in the sample before and after acid activation. All concentrations are expressed as rate of angiotensin generation (ng/ml/h). Angiotensin I was measured by radioimmunoassay. Statistical analysis was performed using Student's 't' test for unpaired samples. All results are presented as mean+/-SEM.

Results: The concentrations of renin and prorenin were highest in the chorion laeve when compared to amnion and placenta (p < 0.01) in both the groups. Furthermore, the concentrations of renin and prorenin were significantly higher in all the tissues from women with pre-eclampsia (p < 0.01).

Conclusion: Renin and prorenin levels are raised in the placental tissues from women with pre-eclampsia. With recent evidence suggesting that both prorenin and renin may have cellular effects independent of angiotensin II generation, there is a need for further study into its role in placentation.