These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Gravitational stress and autonomic cardiac blockade.
    Author: Bjurstedt H, Rosenhamer G, Tydén G.
    Journal: Acta Physiol Scand; 1976 Apr; 96(4):526-31. PubMed ID: 1274625.
    Abstract:
    Arterial pressure, heart rate and cardiac output were recorded in eight healthy, male volunteers in the sitting position at normal gravity (1 G) and during a 4 min exposure in a human centrifuge to 3 G, the G vector in both conditions acting in the head-foot direction. The responses of the observed variables to the change from 1 G to 3 G were compared before and after combined beta-adrenergic and parasympathetic blockade of the heart induced by the i.v. administration of propranolol, 0.25 mg/kg bwt, and atropine, 0.03 mg/kg bwt. After blockade the heart-rate response to increased G averaged 22% of that observed without blockade. Mean arterial pressure at 3 G, and thus G tolerance, was significantly lowered after blockade, resulting in symptoms of retinal hypoxia ("greyout") towards the end of the 3 G runs in some of the subjects. G-induced reductions in cardiac output and stroke volume were significantly larger after blockade. Associated increases in total peripheral resistance were 56% before and 79% after blockade, the stronger vasoconstrictor response in the latter case thus being insufficient for maintenance of arterial pressure homeostasis.
    [Abstract] [Full Text] [Related] [New Search]