Submitted on October 28, 2002
Accepted on December 18, 2002
Effects of prolonged reduction in blood flow on submandibular secretory function in anaesthetized sheep
Avnesh S Thakor1, Christopher N Brown1, and Anthony (Tony) V Edwards1*
1 Physiological Laboratory, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
* To whom correspondence should be addressed. E-mail: ave1000{at}cam.ac.uk.
Submandibular vascular and secretory responses to parasympathetic chorda-lingual (C-L) stimulation were investigated in anaesthetised sheep before, during, and after an intra-carotid (I.C.) infusion of endothelin-1 (ET-1). Stimulation of the peripheral end of the C-L nerve at 4 and 8 Hz produced a frequency-dependent reduction in submandibular vascular resistance (S.V.R.) associated with a frequency-dependent increase in submandibular blood flow, salivary flow, and sodium, potassium and protein output from the gland. During stimulation at 4 Hz, I.C. ET-1 significantly increased S.V.R. (p<0.01), without significantly affecting either the aortic blood pressure or heart rate. Submandibular blood flow (S.B.F.) was reduced by 48±4% and the flow of saliva by 50±1%. The effect on blood and salivary flow persisted for at least 30 min after the infusion of ET-1. The reduction in S.B.F. was associated with a diminution in the output of sodium, potassium and protein in the saliva (P<0.01). These effects persisted for 30 min after the infusion of ET-1 had been discontinued and were linearly related to the flow of plasma throughout.
