REPRODUCTIVE CONDITION, GLOMERULAR ADENOSINE DIPHOSPHATASE ACTIVITY, AND PLATELET-AGGREGATION IN THE RAT - EFFECT OF ENDOTOXIN

In experiment A, the activity of the glomerular antithrombotic enzyme adenosine diphosphatase (ADPase) and the sensitivity of this enzyme fo r endotoxin (1.0 mug/kg BW) in various reproductive conditions of fema le rats were studied through use of enzyme histochemical methods. In e xperiment B, the effect of this dose of endotoxin on the thrombotic te ndency of the glomeruli in pregnant (Pr) and pseudopregnant (PSP) rats was studied by means of ex vivo alternate perfusion of the kidneys wi th human platelets and adenosine diphosphate (ADP). In experiment A, c yclic (C), ovariectomized (OVX), Pr, and PSP rats were infused with en dotoxin or saline. Three days later (for Pr and PSP rats, Day 8), anim als were killed. In intact rats (C, Pr, PSP), the activity of glomerul ar ADPase was the same; however, the activity decreased after OVX. End otoxin decreased the activity of glomerular ADPase in Pr rats only. In endotoxin-treated Pr rats, spontaneously formed platelet microaggrega tes were present in a few glomeruli; in glomeruli of the other groups, microaggregates were not observed. Platelet microaggregates were also present in the venous microvasculature of endotoxin-treated Pr rats a nd, to a lesser extent, in that of other groups, while saline-treated OVX rats were negative in this respect. In experiment B, Pr and PSP ra ts were treated as in experiment A; ex vivo kidney perfusion was perfo rmed on Day 8. Immediately after perfusion, rats were killed. Only Pr endotoxin-treated rats exhibited significantly increased intraglomerul ar platelet aggregation. It was concluded that 1) some ovarian factor maintains the activity of glomerular ADPase at the ''intact'' (glomeru lar ADPase activity of cyclic rats) level; 2) at least one pregnancy-a ssociated factor, possibly of placental origin, is responsible for the increased sensitivity of glomerular ADPase to endotoxin even early in pregnancy; and 3) exclusively in the pregnant rat, endotoxin enhances the thrombotic tendency of the glomeruli by decreasing the ADPase act ivity.