Temporal Correlation Between Intrauterine Oxygen Tension and Endometrial H4-Lactic Dehydrogenase in the Guinea Pig

Abstract

Ambient oxygen tension can alter carbohydrate metabolism of uterine tissue in vitro by modifying the relative proportions of “H” and “M” subunits of lactic dehydrogenase: low oxygen tension favors production of M-LDH wheras elevated pO₂ stimulates H-LDH synthesis (Dawson, Goodfriend and Kaplan, 1964). Previous studies have demonstrated that, in the rat, the luminal surface of the uterus is normally exposed in vivo to alterations in oxygen tension during the estrous cycle (Mitchell and Yochim, 1968a) and pregnancy (Yochim and Mitchell, 1968). Since O₂ tension modifies lactic dehydrogenase isozyme distribution, it was hyposthesized (Yochim and Mitchell, 1968) and subsequently substantiated (Yochim, 1975) that increased intrauterine pO₂ favors the synthesis of H4-LDH in the endometrium and results in increased oxidative metabolism. Thus, in the rat, the concentration of oxygen to which the endometrium is exposed appears to exert a marked effect on LDH isozyme activity. Subsequently, cyclic alterations in intrauterine oxygen tension have also been observed in the guinea pig (Garris and Mitchell, 1979). The following study was therefore undertaken to determine if the relative proportion of H-LDH present in the endometrium of the guinea pig also correlates with changes in intrauterine oxygen tension.