Role of nitric oxide in the regulation of blood flow in the rat submandibular gland during carotid artery occlusion

The possible involvement of nitric oxide in the preservation of blood flow to the rat submandibular gland after uni- or bilateral occlusion of the com mon carotid was studied. Glandular blood Row and mean blood pressure were m onitored before, during and after carotid occlusion in the presence and abs ence of the nitric oxide synthase inhibitor N-omega-nitro-L-arginine-methyl -ester (L-NAME). To calculate vascular resistance, the local perfusion pres sure distal to the point of occlusion was also measured. In normal rats, un i- or bilateral carotid occlusion resulted in an immediate decrease in ipsi lateral glandular blood Row. After the cessation of carotid occlusion, hype raemia was observed in the submandibular gland. Both local perfusion pressu re and vascular resistance decreased during carotid occlusion. In the group pretreated with L-NAME, trends in blood-flow responses to uni- or bilatera l occlusion were identical to those registered in the control groups, thoug h the magnitude of the alterations was significantly less. The well-maintai ned glandular blood Row was due to functioning vascular anastomoses and com pensating dilatation of glandular blood vessels. Nitric oxide had only a re strained effect on this compensatory mechanism. (C) 2001 Elsevier Science L td. All rights reserved.