The action of the depressor nerve on the blood vessels of the liver.

Abstract

1) By stimulating the central end of the depressor nerve of a dog with a tetanic inductive current a decrease in volume of the liver, simultaneous to fall in the general arterial blood pressure and the portal pressure were observed (see exp. 1). This decrease, as shown in fig. 1 is 0.9-2.4cc. and this result is the directly opposite to the reports of Harada (6) and Richter (9), who obtained a 3.1% increase in volume, in experiments with rabbits.2) However, in order to know whether this decrease in the volume of the liver, occurs in the hepatic artery area or in the portal area, the blood flow of the hepatic artery was temporarily occluded, and also the portal blood flow into the liver was constricted as shown in exps. 2 and 3, decrease in the volume of the liver was confirmed in both cases. Namely, due to the depressor reflex, both blood vessels areas show that they are connected with the decrease in the volume of the liver.Harada (6) reports that normally, due to depressor stimulation, there is an increase in volume of the liver, but a decrease, after ligature of the hepatic artery. However, in our experiments, regardless of the existence or non-existence of a blood flow in the hepatic artery, an one-sided change, namely, a decrease in the volume of the liver occured (see exp. 2)3) On the other hand, it may be considered that the liver blood vessels may dilate by the depressor reflex, however the decrease in the general blood pressure and the portal venous pressure caused by the stimulation of the depressor nerve are so much that the dilatation of the hepatic blood vessels can not be observed on the volume change in the liver. However, this observation can be discarded by the perfusion experiment (see exp. 5) or the experiment whereby the blood flow into the liver of both the hepatic artery and the portal vein were shut off (see exp. 4). Namely, in exp. 4, when the hepatic artery and the portal blood flow into the liver were stopped temporarily, no changes occurred in the volume of the liver, due to the depressor reflex (when adrenaline is injected into the liver tissues proper, even after the stoppage of both blood flows, the volume of the liver shows a decrease).Furthermore, as shown in exp. 5, when the perfusion experiment of only the liver in situ, is carried out, even though there may be a fall in the general blood pressure, no change could be confirmed in the volume of the liver.4) Hence the above experiments would indicate that the change in the volume of the liver due to the depressor reflex is a passive one, caused by the fall of the hepatic arterial pressure and the portal venous pressure, and not an active contraction of the hepatic blood vessels.