Abstract
In seven canine heart-lung preparations, norepinephrine was administered in the following doses: 0.04, 0.08, 0.20, 0.40 μg/kg min. The most frequent effects were: (a) fall in pulmonary resistance; (b) fall in pulmonary compliance; (c) increase in pulmonary vascular resistance and pulmonary arterial pressure; (d) fall in coronary sinus blood flow; (e) increase in myocardial contractility; and (f) tachycardia. Propranolol (0.25 mg/kg) blocked norepinephrine effects (e) and (f) reduced the intensity of (b). The local vascular action of norepinephrine which is not blocked by propranolol is responsible for (d) reduction in coronary flow, (c) increase in pulmonary vascular resistance, and even (a) fall in pulmonary resistance. The fall in pulmonary resistance induced by norepinephrine is explained by a local vasoconstriction of bronchial blood vessels. The increase in pulmonary resistance induced by propranolol is explained by a local action, either local spasm of the bronchial muscle, or vasodilation of blood vessels in the bronchial mucosa.
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.
