Action of a water soluble splenic material on anaesthetized rat blood pressure

The effects of a biologically active water-soluble splenic material on the rat blood pressure are described. The endovenous perfusion of the splenic material in acidified and alkalinized forms caused significant increases of the mean blood pressure in normal, vagotomized and pithed rats, showing that, in contradiction to previous reports, changes in pH did not affect its hypertensive activity. In normal rats, the hypertensive responses were not affected by the alpha- and beta-adrenoceptor antagonists: tolazoline, ergotoxine and propranolol, supporting the previously stated view that adrenergic mechanisms are not involved. In addition, the aforementioned results obtained in vagotomized and pithed rats suggest a lack of involvement of cardiac and vascular nervous mechanisms.