The effect of experimental chronic hypertension on tissue plasminogen activator activity, plasminogen activator...

Chronic hypertension was induced in rats after partial nephrectomy. The systolic blood pressure was significantly elevated from the first week after nephrectomy to the end of the experimentation (8th week). Plasminogen activator activity (PAA) and plasminogen activator inhibition (PAI) showed a tissue- and time-dependent pattern of changes in some key organs compared to controls (sham-operated rats). Two weeks after nephrectomy (one week after the induction of hypertension) the PAA was markedly increased in lungs, heart and aorta. In aorta the PAA continued to be enhanced until the end of the experimentation (the 8th week after nephrectomy), while in heart and lungs the PAA returned to the normal eight weeks after nephrectomy. In vena cava, brain and liver no change in PAA was noticed compared to controls. Tissue PAI was mostly increased or unchanged, while tissue plasmin inhibition (PI) was unchanged. The differential response of PAA and PAI was varying not only from one organ to another or in the same organ at a given time but also in the same organ throughout experimentation. In a number of nephrectomized rats, however, hypertension was not induced. In these rats similar changes in tissue PAA and PAI were noted compared to hypertensive nephrectomized rats. Therefore, all the changes in the parameters studied should be due to the partial nephrectomy itself. In conclusion, experimentally induced chronic hypertension had not any effect on tissue PAA, PAI and PI.