Regional differences in blood flow variation in rat masseter muscle

Abstract 

Regions of a belly in a masseter muscle have been suggested to be activated independently in order to enable complex jaw-movements. However a regional difference of the masseter blood flow (MBF) is still unclear although the blood flow is one of the most important factors during activation of the muscle. The present study examined regional differences in blood flow in rat masseter muscle by comparing blood flow values at the inferior, centre, superior, anterior, and posterior regions of the muscle belly using a laser speckle imaging flowmeter with or without sympathetic and parasympathetic stimulation. Regional differences in blood flow levels were observed in each region of the masseter muscle belly during rest. Additionally, amplitudes of blood flow changes evoked by electrical stimulation of parasympathetic and sympathetic nerves differed among regions. These results demonstrate the regional differences in hemodynamics during rest, sympathetic vasoconstriction (including the recovery phase), and parasympathetic vasodilatation in rat masseter muscle.

Abbreviations: CST, cervical sympathetic trunk, LDF, laser-Doppler flowmeter, LSI, laser speckle imaging, MBF, masseter blood flow, SABP, systemic arterial blood pressure

Keywords: Laser speckle imaging, Masseter muscle, Blood flow, Sympathetic vasoconstriction, Parasympathetic vasodilatation