線溶活性の組織化学的研究

動物種属間における正常膀胱壁の tissue plasminogen activator

抄録

Continuing our studies on the biochemical and histochemical distribution of fibrinolytic activity in the various epithelial cells, we wish to report comparative observations on the localization of tissue plasminogen activator in the normal bladder wall of mice, rats, guinea pigs and rabbits which are widely used in experimental studies using the histochemical fibrin slide techniqe.
A few similar histochemical comparative study deals with rat and human bladder wall. Such a study is of particular interest because the transitional epithelium cells of urinary tract has a special role in physiology of fibrinolytic systems.
In all instances, the same sequence of fibrinolytic activity was demonstrated, rats and guinea pigs being highly active, rabbit less so and mice only weakly active; the fibrinolytic activity was found in relation to some vessels in the muscular coat or the submucosa, the transitional epithelial lining and the desquamated cells of all animals studied. These findings were practically similar pattern with the localization of fibrinolytic activity in the bladder wall of rat and man as described recently.
It was also found that the bladder wall can be stored at least one month under keeping in sealed plastic bags to prevent evaporation at temperature of -20°C or lower without significant loss of fibrinolytic activity, although the prolonged storge in the refrigerator to which the bladder had been exposed has had a slight disturbing effect on the epithelial cells.
The fibrinolytic activity in the bladder wall was not produced by a direct effect of fibrin splitting protease, and it indicated that the pronounced lysis of the plasminogen-rich fibrin demonstrated in all animal species studied was caused by a plasminogen activator released by the bladder epithelial cells and vascular endothelial cells.
The position of plasminogen activator at the bladder epithelial cells would suggest that the urinary tract is protected itself from urokinase which is fibrinolytically very stronger and fibrinolysis at the bladder epithelium could assist in removeing fibrin or foreign bodies deposits which produce a nucli of urinary calculus in pathological conditions.
The serection of the preffered laboratory animals except mouse in experimental studies of reparative bladder epithelium formation could perhaps be explained by the similar pattern of fibrinolytic activity in its tissues.