Abstract
Experimental arterial hypertension has been induced in dogs by means of two different methods. In a series of dogs, the 4 moderator nerves (2 aortic and 2 carotid sinus nerves) were cut: both carotid sinuses were completely excised, one cervical aortic-sympathetic-vagus nerve was cut and out of the other aortic-sympathetic-vagus nerve, the aortic and sympathetic fibers were dissected and cut, leaving only a small bunch of vagal fibers sufficient to avoid the accidents of bilateral cervical vagotomy. This technic induces a permanent high blood pressure up to 320 mm Hg for several months. In another group of dogs, chronic arterial hypertension was induced by the permanent compression of the renal arteries, according to Goldblatt's technic.
In order to test the presence of vasopressor substances in the blood of these dogs suffering from chronic hypertension, the following technic was used: In a normal dog, anesthetized with chloralosane and sensitized to vasopressor substances by means of cocaine injection, the volume of the spleen is registered by means of a very sensitive plethysmograph after one branch of the splenic artery has been ligated and prepared for intrasplenic arterial injections. By means of this method, it is possible to register a decrease in the spleen volume caused by an injection into the splenic circulation of adrenalin in amounts as small as 10-5 mg.
The vasopressor activity of the arterial blood (1-20 cc) of hypertensive dogs, obtained by femoral puncture and immediately injected into the splenic circulation of the test dog, was tested by means of this very sensitive preparation. These experiments showed that the blood of dogs rendered hypertensive by section of the moderator nerves, possesses, on an average, a higher vasopressor activity than the blood of normal dogs.
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