Abstract
This study was undertaken to determine if the sympathetic discharge which accompanies hemorrhagic shock modifies the response to tyramine. In eight dogs the dose of tyramine equipressor to 1.0 µg/kg min of norepinephrine was 85 ± 8 µg/kg min in the control state, but had risen to 301 ± 55 µg/kg min after 4 hr of hypotension. In four dogs in which the norepinephrine pool had been labeled with tritiated norepinephrine, injection of tyramine into femoral arterial blood released large quantities of norepinephrine into the femoral venous blood during the control period. After 4 hr of hypotension, the output of radioactive norepinephrine by tyramine was greatly reduced. These findings support the view that the diminished responsiveness to tyramine after prolonged hypotension is due to decreased release of norepinephrine. Since there was no detectable decrease in the norepinephrine concentration of atrial appendage in eight dogs after 4 hr of shock, the diminished release of norepinephrine by tyramine in shock may have been due to the depletion of the small portion of the norepinephrine store releasable by tyramine.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
