Difference in the activating effect on normal and hypertensive plasma on intestinal segments treated with renin

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379

ABSTRACTS

holding venous pressure at high levels by intravenous infusion of acacia-Locke’s solution fails to restore normal arterial pressure in these animals. In pithed rabbits a rise in arterial pressure is easily evoked with epinephrine; the response is greater in those which have had renal hypertension for several months, but not in hypertensive rabbits nephrectomized thirty hours before pithing. No rise in venous pressure precedes the rise in arterial pressure. Renin, like epinephrine, causes a rise in arterial pressure in pithed rabbits, and thus differs from the humoral agent causing chronic renal hypertension. The latter apparently changes the reaction of the vasomotor center so as to maintain pressure at high levels. It also increases the sensitivity of the arterial response to epinephrine. AUTHOR. Page, Irvine H.: Demonstration Stream Prom Kidneys of Perinephritis. Am. J. Physiol.

of the Liberation of Benin Animals Made Hypertensive 130: 22, 1940.

Into by

the Blood Cellophane

Renin is liberated into the renal vein in increased amounts by the kidneys of dogs made hypertensive by cellophane or silk perinephritis, and by clamping the renal artery. Most of it disappears by the time the bload has reached the femoral artery. Renin-activator is decreased in t.he blood from the renal vein and is increased in hypertensive animals when the femoral artery is reached. Angiotonin-activator is not greatly decreased in the rena.1 vein blood but may be increased in the femoral arterial blood in hypertensive animals. Early in the course of malignant hypertension, large amounts of renin are Later, both angiotonin-activator liberated by the kidneys (one experiment). and renin-activator are greatly reduced or sutlicient inhibitor is formed to abolish the reaction batween them and angiotonin or renin (seven experiments). AUTHOR Page, Irvine Plasma 29, 1940.

H.:

Difference

on Intestinal

in the Activating

Segments

Treated

Effect

With

on Normal and Hypertensive .Am. J. Physiol. 130:

Renin.

The reaction between renin and renin-activator is a specific one and the product of this reaction-angiotonin-causes strong contraction of isolated intestinal segments. This reaction has been employed to ascertain the rerun-activating power of plasma. Heparinized plasma derived from blood of some patients with essential hypertension causes greater renin-activation than does normal human blood. Plasma from dogs with experimental hypertension also exhibits this heightened power compared with plasma of normal dogs. This suggests that the humoral mechanism in the two types of hypertension have much in common and that the hypertensive either has increased amounts of renin-activator in the blood, or decreased amounts of renin-inhibitor, or both. AUTHOR. Sweeney, H. Xorrow: Systemic Blood

Do the

Pressure

Carotid

Is Low?

Sinuses Exert a Pressor Activity Am. J. Physiol. 130: 186, 1940.

When

the

Lowering of the blood pressure in dogs anesthetized with chloralose ‘to sustained low levels varying from 45 to 70 mm. Hg does not arouse any pressor activity in the carotid sinuses, which, if present, would be demonstrable by a fall in pressure when these areas were denervated. A gradual rise in pressure in ten of the