H. Aars et al., A STUDY OF CHOLINERGIC AND BETA-ADRENERGIC COMPONENTS IN THE REGULATION OF BLOOD-FLOW IN THE TOOTH-PULP AND GINGIVA IN MAN, Acta Physiologica Scandinavica, 148(4), 1993, pp. 441-447
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.