Abstract
The influence of the sympathetic and parasympathetic nerves on the intrahepatic vascular system has been deduced mainly from indirect evidence based on data obtained from plethysmographic changes in volume of the liver and from changes in hepatic inflow or outflow, as well as from variations in portal pressure during stimulation of the nerves. The object of this study was to observe directly, by transillumination of the intact liver in the anesthetized animal the effect of stimulation of the sympathetic and parasympathetic nerves on the intrahepatic vessels and to determine whether or not the intrahepatic vascular system possesses an active vasoconstrictor or an active vasodilator mechanism or both.
The literature on the subject discloses a number of different views held by investigators who employed various methods for determining the effect of stimulation of the autonomic nerves on the vascular ramifications within the liver. Bayliss and Starling 1 obtained a rise in portal pressure by electric stimulation of the splanchnic nerves. Cavazzani and Manca 2 produced constriction of the portal radicles by asphyxia after sectioning the vagus nerves, but not after sectioning the splanchnic nerves. They stated that the vagus nerves cause direct and not reflex dilation of the portal radicles within the liver. In another publication they reported that the intrahepatic branches of the hepatic artery constrict during vagal stimulation and dilate during stimulation of the celiac plexus. François-Franck and Hallion 3 obtained a decrease of hepatic volume and a rise of portal pressure in the dog when the splanchnic nerves were stimulated. The same results were obtained after ligation of the hepatic artery.
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