Regional blood flow effects of ANP in conscious dogs: preferential gastrointestinal vasoconstriction.
We studied total and regional blood flow responses to human atrial natriuretic peptide (alpha-hANP) using radioactive microspheres in six conscious dogs. Hemodynamic responses to infusions of alpha-hANP at 75 ng.kg-1.min-1 were determined in each dog in the presence and absence of autonomic reflexes using the ganglion blocking agent pentolinium. When autonomic reflexes were blocked, alpha-hANP caused a substantial reduction in gastrointestinal (GI) vascular conductance (35%) but had no significant effects in brain, kidneys, liver, skeletal muscle, or skin. This alpha-hANP-induced fall in GI conductance contributed more than 40% to the fall in total peripheral conductance (TPC) of 24% occurring after autonomic blockade. A fall in myocardial vascular conductance, most prominent in the left ventricle, contributed a further 40% to the fall in TPC. When autonomic reflexes were intact, alpha-hANP caused vasoconstriction in the GI region (29% fall in vascular conductance), had no significant effects on myocardial vascular conductance but significantly increased splenic vascular conductance. In addition to these systemic responses, alpha-hANP infusion also significantly reduced pulmonary vascular conductance, independent of autonomic reflex activity or changes in pulmonary artery pressure. Thus our results in conscious dogs demonstrate that alpha-hANP causes a systemic vasoconstriction, most pronounced in the GI region.
Woods
R L
RL
Baker Medical Research Institute, Prahran, Victoria, Australia.
Smolich
J J
JJ
D000818:Animals; D001011:Aorta / Q000502:physiology; D016275:Atrial Function / Q000187:drug effects; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001340:Autonomic Nerve Block; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004064:Digestive System / Q000098:blood supply*; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008863:Microspheres; D010101:Oxygen Consumption / Q000187:drug effects; D010425:Pentolinium Tartrate; D011312:Pressure; D011651:Pulmonary Artery / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*
D009320:Atrial Natriuretic Factor; D010425:Pentolinium Tartrate