Abstract
We examined whether pressor responses to isometric biting were partially caused by sensory receptors in periodontal tissue through increased MSNA and attenuated baroreflex gains in humans. First, we measured muscle sympathetic nervous activity from the peroneal nerve (MSNA, microneurography), arterial pressures (AP, finometer), heart rate (HR), electromyogram of masseter muscle (EMG), biting force (BF), and finger skin blood flow (FSBF, laser-Doppler flowmetry) during 2-min isometric biting at 50% maximal voluntary contraction (MVC) before (No-Blk) and after pharmacological alveolar nerve block (Blk) in 8 young men. Second, baroreflex gain was determined by the Oxford method during 5-min periods of rest without biting (No-BT) and biting at 30%MVC (BT) in Blk and No-Blk, respectively. In the 1st study, biting increased AP, HR, and total MSNA (burst amplitude x frequency) and decreased finger cutaneous vascular conductance (FCVC, FSBF/mean AP) in Blk and No-Blk (P<0.05). However, the increases in AP, total MSNA, and the decrease in FCVC were markedly less in Blk than in No-Blk (P<0.05) with no differences in EMG, BF, and HR response between the trials. In the 2nd study, baroreflex gains from HR (HR/systolic AP) and MSNA (total MSNA/diastolic AP) responses to pharmacologically altered AP were lower in BT than in No-BT (P<0.05) for no-Blk, while the differences disappeared in Blk. Thus, the sensory receptors in periodontal tissue were involved in pressor response to isometric biting through increased MSNA and reduced baroreflex gains. [J Physiol Sci. 2007;57 Suppl:S205]
