[What does the relation of digoxin-like immunoactivity and serum insulin levels in pregnant women signify?].

BACKGROUND: Digoxin-like immunoactivity (DLIA) reflects the presence of endogenous substances which are close to cardiac glycosides. These substances via inhibition of Na(+)-K(+)-ATPase increase intracellular calcium stores (Ca2+i) and may modulate various Ca(2+)-dependent mechanisms. Although DLIA are known primarily as hypertension and natriuresis promoting factors, several recent works have suggested that DLIA relates also to diabetes mellitus. The main stimulus for DLIA secretion represents volume-expansion. AIM OF STUDY: To assess relation of DLIA to glucose tolerance and insulin levels in pregnant women (PW). SUBJECTS AND METHODS: 1) 67 PW (DLIA measured by RIA-kit HUMA-LAB Kosice), 2) 53 PW (DLIA measured by RIA-kit ORION). PW were subdivided according to the glucose tolerance and insulin concentrations. RESULTS: 1. DLIA in hyperinsulinemic PW were significantly higher than in those with normal insulin levels. 2. DLIA significantly correlated with insulin levels as well as with insulinogenic index. 3. The increase in plasma glucose and insulinemia during OGTT was accompanied by a decrease in DLIA. These findings were independent of other measured parameters (age, body mass index, pregnancy induced weight gain, blood pressure and steroid hormones). CONCLUSIONS: These findings suggest that DLIA does not respond only to changes regarding sodium-retention and volume-expansion, but also to changes in glucose and insulin metabolism. Thus, DLIA could represent one of the markers of "specific" neurohumoral activation. However, the question of whether an elevation in DLIA may consequently modulate mechanisms of insulin secretion, insulin sensitivity, vascular reactivity and other Ca2+i-dependent mechanisms remains speculative. (Tab. 4, Fig. 4, Ref. 41).