Very little is presently known about reflex autonomic effects from abdominal visceral stimulation. This proposal therefore will examine the cardiovascular, respiratory and visceral responses to afferent stimulation in the gallbladder, pancreas, large and small intestines, and mesentery of feline and canine species. Comparisons of the reflex respiratory effects will be made with stimulation of afferents in skeletal muscle. Stimuli will include local application and close arterial injection of both pharmacological and physiological substances as well as mechanical and metabolic (e.g., exercise) pertubations. In these studies, the afferent fibers activated will be studied with single unit recordings. Efferent pathways will be determined by integration of whole nerve activity, nerve transection and altered end organ function. Specific end organs to be studied include the heart, lungs, trachea, stomach, intestines, urinary bladder and regional circulations of those and other organs. Assessment of preload, afterload and myocardial function will be used to assess the heart. Trachealis smooth muscle tension, tantalum bronchograms and pressure-flow curves will be used to assess respiratory function. Viscus wall tension, determined by balloon pressure, will be used as a measure of abdominal organ function. The radioactive microsphere and isolated perfusion techniques will provide measures of regional vascular reactivity. Interactions between abdominal visceral and cardiopulmonary or baroreceptor afferents likewise will be examined. These studies will provide a new understanding of somatic and visceral abdominal reflex activation of the autonomic nervous system. This information may then provide a rationale for the management of somatic or abdominal pain and inflammation in the context of surgical manipulation as well as in a variety of physiological and pathological situations.
