Regional blood flow effects of ANP in conscious dogs: preferential gastrointestinal vasoconstriction
Woods, R.L.; Smolich, J.J.
American Journal of Physiology 261(6 Pt 2): H1961-H1969
1991
ISSN/ISBN: 0002-9513 PMID: 1836313 Document Number: 370169
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 .cntdot. kg-1 .cntdot. 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.