The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.

One of the characteristics of the pressor substance which may cause essential hypertension in man or experimental renal hypertension in dogs must be an ability to elevate arterial pressure by constricting the arterioles sufficiently to increase peripheral resistance but not sufficiently to reduce blood flow. Clinical experience indicates that patients or animals with hypertension do not have cold, pale skin indicative of reduced blood supply. On the contrary, the plethoric appearance of many such patients is well known.Experiments, both on animals and man, show that the ability of pressor substances to cause vasoconstriction varies greatly, not only in the same, but in different segments of the vascular system. For example, pitressin and adrenalin have in common the ability to reduce blood flow severely while the former elevates arterial pressure but little and the latter strongly. As Landis, Montgomery, and Sparkman (1) pointed out, pressor agents which severely reduce blood flow to the periphery in relation to their ability to raise blood pressure, could scarcely be expected to be concerned in the genesis of hypertension characterized by normal or even elevated peripheral blood flow. They found in rabbits that renin was unusual among the other pressor substances in elevating arterial pressure without consistent reduction of skin temperature, --which was accepted as a rough measure of peripheral blood flow.The demonstration that renin itself was not a pressor substance but produced elevation of pressure only after interaction with renin-activator and the liberation of angiotonin (2, 3) required that it also be shown that purified angiotonin elevates arterial pressure without significant fall in peripheral blood flow.Corcoran and Page (4) found no consistent change in skin temperature of trained normal dogs when angiotonin was infused. Both renin and angiotonin *An abstract of this paper was published in the Biological Bulletin, 1940, 79~ 357. 305

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1. The present experiments demonstrate by direct observation that peripheral arterioles in moat chambers in rabbits' ears constrict during the development of renal hypertension, and that they remain persistently constricted, although not sufficiently to interrupt the blood supply to the tissues. The arteriolar constriction in the hypertensive animals was not dependent upon nerves, since it occurred in newly formed arterioles which had probably never been supplied with nerves, as well as in older arterioles with a functional nerve supply. 2. No capillary constriction was observed during or following the development of hypertension, although the walls of the capillaries could be very clearly seen. Persistent hypertension was associated in two examples with increased sticking of leukocytes to the walls of the capillaries and venules, some emigration of leukocytes, and a few small hemorrhages. 3. During development of hypertension, new arteriovenous anastomoses were observed to appear in the chambers. 4. No evidence of change was noted in the viscosity of the blood or in the appearance of the blood corpuscles in the hypertensive rabbits. 5. The constriction of the arterioles during and following the development of hypertension closely resembled that produced by intravenous injections of angiotonin.

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