A STUDY OF CHOLINERGIC AND BETA-ADRENERGIC COMPONENTS IN THE REGULATION OF BLOOD-FLOW IN THE TOOTH-PULP AND GINGIVA IN MAN

In 10 subjects, laser Doppler flowmetry was used to study whether chol inergic or beta-adrenergic pathways are involved in the control of too th pulp blood flow (PBF) in response to isometric hand grip and the co ld pressor test. We also examined if differences exist between the reg ulation of blood flow in the tooth pulp and the nearby gingiva (GBF). Isometric hand grip (35% of maximum force, 2 min) and the subsequent i schaemia (2 min) induced a brief rise in PBF and a more long-lasting r ise in GBF. Atropine increased heart rate about by 40% and changed the pulpal response to a fall in flow, without altering gingival flow. Pr opranolol, causing a 20% reduction in heart rate, had no effect on eit her flow during the actual test, but induced a rise in GBF after the i schaemic period. The cold pressor test (2 min at 0.5-degrees-C) result ed in a reduction in PBF and GBF, unaffected by the blocking drugs. Wi th atropine, however, PBF increased immediately after this test. The r elative changes in arterial pressure and heart rate were unaffected by the drugs. Our study has demonstrated the existence of cholinergic ne rvous vasodilation in vessels serving the tooth pulp. Non-adrenergic n on-cholinergic mechanisms probably contribute to the evoked rise in GB F during exercise. Beta-adrenoceptors are involved in the control of G BF immediately after isometric exercise. While the two tests under con trol conditions evoked mostly parallel changes in PBF and GBF, the use of blocking agents showed that blood flow is controlled by different mechanisms in the two adjacent vascular beds.