The Effects of Some Reflex Stimuli Hypoxia and Hypercapnia on the Resistance Blood Vessels in the Forearm and Hand of Patients with Vasoregulatory Asthenia

Journal/Book: Acta Soc. Med. Upsal. 70 263-278 (1965).-. 1965;

Abstract: From the Department of Clinical Physiology The University Hospital (Akademiska sjukhuset) Uppsala Sweden Abstract Investigations were made on 11 patients with vasoregulatory asthenia (VA) and 12 clinically healthy control subjects (CS) of the circulatory reactions (a) in the forearm due to raising of the legs resisted breathing or a Valsalva-like manuvre (b) in the forearm and hand due to breathing 5%CO2 in air or 9.5%O2 in nitrogen. The blood flow was measured by venous occlusion plethysmography. Raising of the legs or forced resisted breathing caused signs of a decrease and the Valsalva manuvre of an increase in forearm vascular resistance. These changes were more pronounced in the VA patients. Blockade of the deep forearm nerves abolished both reactions. Breathing 5%CO2 in air caused signs of an increase of vascular resistance in the hand in all subjects while signs of a decrease of vascular resistance in the forearm occurred in CS but not in VA. After blockade of the deep forearm nerves signs of a decrease of vascular resistance in the forearm on the inhalation of 5%CO2 in air were also found in the VA patients. Breathing 9.5%O2 in nitrogen caused signs of an increase in the hand vascular resistance in all subjects but of a marked decrease of vascular resistance in the forearm which was greater in VA than in CS. This decrease in resistance remained unchanged after blockade of the deep forearm nerves and was therefore probably not due to reflex alteration of the sympathetic vasoconstrictor tone. It is concluded that the sympathetic vasoconstrictor tone in the forearm (mainly muscle) vessels of the VA patients was of the same if not higher basal intensity as in the healthy subjects and that reflex changes could be evoked. ___MH

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