Cardiac receptor modulation of blood flow and fluid transport in feline jejunum

The aim of the study is to determine the effects of selective cardiac receptor unloading on vascular resistance and net fluid transport in the small intestine. In anesthetized cats, cardiac receptors were unloaded by positive pressure ventilation (PPV). Arterial baroreceptor activity was artificially maintained constant. To test if the observed responses were due to a vagal reflex, experiments were performed both in animals with intact vagal nerves (n = 9) and after bilateral cervical vagotomy (n = 8). PPV-induced decreases in central blood volume (CBV) significantly increased intestinal vascular resistance (IVR) and net fluid absorption rate and decreased the transmural potential difference (PD). Cervical vagotomy per se also increased IVR and absorption rate and decreased PD. In vagotomized animals, decreases in CBV had no consistent effects on IVR, net fluid absorption rate, or PD. The results are compatible with cardiac receptor modulation of both blood flow and fluid absorption rate in the feline jejunum. Differences in the response patterns for the vascular and absorptive effects suggest that they may be mediated by separate efferent pathways.