Removal of the submandibular glands increases the acute hypotensive response to endotoxin

We investigated the roles of the submandibular glands and of their sympathetic innervation on the acute hypotensive response induced by the i.v. injection of endotoxin (10 mg/kg; Salmonella typhosa) into rats anesthetized with sodium pentobarbital. Endotoxin given to unoperated and sham-operated rats induced a transient 30-40 mm Hg drop in blood pressure. Rats that had their submandibular glands removed (sialadenectomy) or bilateral resection of the superior cervical ganglia (ganglionectomy), exhibited significantly larger drops in blood pressure (approximately 65 mm Hg) that were maintained for the 60 min of the experiment. This increased responsiveness to endotoxin in sialadenectomized and ganglionectomized animals was not related to changes in haematocrit, white blood cell counts, or neutrophil activity. Pretreatment of rats with pentoxifylline (PTX) produced substantial protection against the hypotensive effects of endotoxin in ganglionectomized and sialadenectomized rats, although this xanthine did not affect the responses of sham-operated rats. These results suggest that the submandibular gland elaborates a factor that protects against acute hypotension induced by endotoxin and that this factor is under the control of the cervical sympathetic nervous system.