Effect of clonidine on three types of experimental hypertension and on plasma renin activity in dogs]

Intra-cisternal clonidine (3 microgram/kg) reduced hypertension and cardiac acceleration after defrenation in dogs, but did not act in intra-venous infusion (10 microgram/kg). The renin activity was not modified. Clonidine was always inactive on hypertension after stimulation of visceral afferences or after injection of potassium cyanidine. These results show that a central mechanism was implied in the anti-hypertensive action of clonidine.     

Effect of the alpha-adrenoblocker pyrroxan on systemic hemodynamics in puppies and dogs with vasorenal hypertension]

Vasorenal hypertension was induced in 2--3-month-old puppies and adult dogs by stricture of both renal arteries. 1.5 mg/kg of pyrroxan was injected intravenously 3 and 14 days later. A reduction of increased arterial pressure was noted both in adult dogs and in puppies, to the subnormal level in the latter. Hypotensive effect of the preparation was connected in adult animals with diminution of the general peripheral vascular resistance and in puppies, besides, with reduction of cardiac output. Pyrroxan injection was accompanied in all the animals with tachycardia, reduction of the phase of isometric contraction and activation of myocardial contractility.     

The effect of interleukin-2 on experimental emotional hypertension]

The effect of human recombinant interleukin-2, one of the potent mediators of the immune system, on the course of emotional hypertension in non-linear white rats has been investigated. A significant and prolonged hypotensive action of a single injection of interleukin-2 in hypertensive rats has been revealed. The data obtained can be a new evidence of participation of immune system in the development of hypertension in experimental animals.     

Effect of hypertension on elasticity and geometry of aortic tissue from dogs

Inflation-extension experiments were carried out on segments of the descending thoracic aortas from 4 normotensive and 4 hypertensive dogs rendered hypertensive using either unilateral or bilateral renal artery constriction. Intravascular pressures up to 200 mm Hg and axial forces up to 200 g were used. The external diameter of the segment and the distance between two longitudinally spaced gage marks were recorded photographically at each pressure-force level combination. Dimensions in the underformed configuration were measured at the end of the inflation-extension experiment. Data were analyzed for changes in geometry and force-deformation response. Results indicate that: 1. Under sustained hypertension the wall thickness in the underformed configuration increases with a concurrent reduction in the in-situ longitudinal extension ratio. 2. This dual tissue response accomplishes substantial reductions in the circumferential and longitudinal stresses from the levels that would be reached at equivalent pressures in the absence of these geometric changes. 3. At comparable intravascular pressures the extensibility in the circumferential direction is slightly greater for the hypertensive aortas as compared to normals. However, the stress-extension ratio relationship in the circumferential direction is similar in the two groups. 4. The stress-extension ratio relationship in the longitudinal direction indicates that the hypertensive aorta is stiffer than its normotensive counterpart.     

Effect of experimental neurosis on the secretion of acid gastric proteinases in dogs

In experiments on dogs with gastric cannula we proved that the gastric juice, obtained after intravenous injection of insulin, contained after separation of DEAE Sephadex A-50 5--7 proteolytically active fractions. In four dogs of both sexes the ratio and number of individual fractions remained constant in control experiments. However, there were differences between the animals. After induction of experimental neurosis (by the collision of the alimentary and avoidance reflex) all animals showed the same marked changes in the chromatographic patterns of acid proteinases. There was a change not only in the ratio of two larger groups of proteolytically active fractions but also in the total number of all fractions. These changes persisted for 8--10 weeks after induction of experimental neurosis.     

Effect of reinnervation on the state of transplanted kidneys in dogs]

In the experiments lasted for 2 years, the effect of surgical reinnervation on the morphofunctional state of autotransplanted and denervated kidney was studied in 175 dogs. General morphological, impregnational, special neurohistological investigations and kidney scanning demonstrated that 2 months after surgical reinnervation of the autotransplantated and denervated kidneys, active sprouting of nerve fibers, adrenergic and cholinergic including, was started along the degenerated nerve trunks, and by the 4th month the nerve fibers reached the renal glomeruli, tubules and pelves. A rather complete restoration of the organic innervation resembling that of the intact organ provided stability of the general morphological structure in the reinnervated kidney, its functional ability and prevented atrophy, sclerosis and stable functional depression observed in cases of renal transplantation and denervation without surgical reinnervation. From this point of view, the problem of necessary active surgical reinnervation of the renal transplantation is discussed.