Effects of sympathetic nerve activity on changes in the position of the rabbit incisor tooth evoked by acute alterations in arterial blood pressure.
The influence of the sympathetic innervation of periodontal blood vessels on the responses of the upper incisor tooth to sudden changes in mean arterial pressure was studied in 15 anaesthetized rabbits. Changes in axial position of the tooth were measured by ultrasonic transit time technique. With intact sympathetic nerves, the tooth showed small, if any, intrusive movements in response to 6-42 mm Hg reductions in arterial pressure evoked by stimulation of the aortic baroreceptor nerve. When exposed to similar periods of hypovolaemic hypotension, the intrusions were, on an average, 1 micron larger (p less than 0.01). After bilateral sectioning of the cervical sympathetic nerves, tooth intrusions in response to both types of pressure reduction became more marked, as did the extrusive movements evoked by abrupt increases in aortic pressure (produced by inflation of intra-aortic balloon). After sympathectomy, a 19 +/- 6 mm Hg rise in pressure caused extrusions of 6 +/- 3 microns, or 2 microns more than before the sympathectomy (p less than 0.01). The results suggest that the activity in sympathetic nerves to periodontal blood vessels may be inhibited by central nervous mechanisms and that the sympathetic innervation of the periodontal vasculature serves to minimize changes in tooth position brought on by sudden alterations in arterial pressure.
D000818:Animals; D001794:Blood Pressure; D007180:Incisor / Q000502:physiology*; D010519:Periodontium / Q000098:blood supply; D011311:Pressoreceptors / Q000502:physiology; D011817:Rabbits; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000502:physiology*; D014086:Tooth Mobility