DIGITALIS-LIKE FACTOR AND DIGOXIN-LIKE IMMUNOREACTIVE FACTOR IN DIABETIC WOMEN WITH PREECLAMPSIA, TRANSIENT HYPERTENSION OF PREGNANCY, AND NORMOTENSIVE PREGNANCY

An endogenous sodium pump inhibitor, or digitalis-like factor (DLF), h as been postulated to mediate essential hypertension. It may also play a role in preeclampsia. However, studies of this factor in hypertensi ve pregnancy have not provided consistent findings. Part of this may b e due to the absence of subclassification of pregnant women with pregn ancy-induced hypertension (PIH) when assessing these parameters. In th is study we explored serum DLF and digoxin-like immunoreactive factor (DLIF) in insulin-dependent diabetic (IDDM) women with normotensive pr egnancies or PIH, comparing them to each other and to nondiabetic preg nant women. Our results demonstrated that nondiabetic women with preec lampsia (PE, PIH with proteinuria) had significantly increased serum D LF and DLIF compared to normotensive pregnant women (NL BP). Women wit h transient hypertension of pregnancy (THP, PIH without proteinuria) h ad intermediate values (DLF. NL BP: 3.3 +/- 0.6, THP: 4.8 +/- 1.1, PE: 7.6 +/- 1.3% inhibition [Na,K]-ATPase, P < .05 ANOVA; DLIF. NL BP: 0. 22 +/- 0.02, THP: 0.28 +/- 0.03, PE: 0.35 +/- 0.02 ng digoxin equivale nts/mL, P < .05 ANOVA). Pregnant normotensive IDDM women had significa ntly higher serum DLF and DLIF activity than their nondiabetic counter parts (DLF. non-IDDM NL BP: 3.3 +/- 0.06 v IDDM NL BP: 8.8 +/- 1.2% in hibition [Na,K]-ATPase, P = .0008; DLIF. non-IDDM NL BP: 0.22 +/- 0.02 v IDDM NL BP: 0.31 +/- 0.02 ng digoxin equivalents/mL, P = .005). How ever, in the IDDM pregnant women, serum levels of DLF and DLIF were no t significantly increased further with PIH (DLF. NL BP: 8.8 +/- 1.2, T HP: 6.9 +/- 2.8, PE: 6.1 +/- 1.4% inhibition [Na,K]ATPase, P = NS ANOV A; DLIF. NL BP: 0.31 +/- 0.02, THP: 0.36 +/- 0.07, PE: 0.38 +/- 0.04 n g digoxin equivalents/mL, P = NS ANOVA). These results suggest that in nondiabetic pregnant women, DLF and DLIF are only significantly incre ased in preeclampsia. Moreover, in IDDM pregnant women, the presence o f increased DLF and DLIF in normotensive subjects and the absence of a significant further increase in subjects with PIH suggests that hyper tension in these women may differ mechanistically from PIH in nondiabe tic women. Lastly, inclusion or exclusion of diabetic pregnant women c an lead to different results for DLF in PIH.