Plethysmographic Studies on Vasomotor Regulation in Stomach, Intestine and Skin.

It has been attempted to clarify regional differentiation of vasomotor control in urethane-chloralose anesthetized cats. For this purpose, vasomotor patterns of gastric, intestinal and cutaneous blood vessels have been investigated by means of a photoelectric plethysmography. Following an intravenous administration of a small dose (5 mg/kg) of pentobarbital, paw volume pulse showed a remarkable, sometimes enormous, increase in amplitude, whereas gastric and intestinal volume pulses were only slightly augmented. Occlusion of bilateral carotid arteries caused a rise of systemic blood pressure. At the same time, volume pulse amplitude was usually decreased in the paw, while in most cases increased in the stomach and intestine. That is, the resistance vessels of the paw was more affected in this homeostatic reflex than those of the gastrointestinal tract. It was also noticed that the baseline of paw plethysmogram was lowered during carotid occlusion irrespective of changes in volume pulse amplitude. The result suggests veno-constriction in the paw. Intravenous gastrin augmented volume pulses in the stomach as well as in the intestine, but reduced in the paw. It was concluded that a positive correlation exists between secretion and blood flow after intravenous gastrin. The results were discussed in terms of their functional significances.