Sympathetic control of the coronary circulation during trigeminal nerve stimulation in humans

Abstract

Purpose: We sought to investigate the sympathetic mechanism controlling coronary circulation during trigeminal nerve stimulation in healthy women.

Methods: The protocol consisted of 3 min of trigeminal nerve stimulation (TGS) with cold stimuli to the face, in two conditions: (1) control and β-blockade (oral propranolol), and (2) control and α-blockade (oral prazosin).

Results: Thirty-one healthy young subjects (women: n = 13; men: n = 18) participated in the study. By design, TGS decreased heart rate (HR), and increased blood pressure (BP) and cardiac output (CO). Before the β-blockade coronary blood velocity (CBV-Δ1.4 ± 1.3 cm s^-1) increased along with the decrease of coronary vascular conductance index (CVCi-Δ-0.04 ± 0.04 cm s^-1 mmHg^-1) during TGS and the β-blockade abolished the CBV increase and a further decrease of CVCi was observed with TGS (Δ-0.06 ± 0.07 cm s^-1 mmHg^-1). During the α-blockade condition before the blockade, the CBV increased (Δ0.93 ± 1.48 cm s^-1) along with the decrease of CVCi (Δ-0.05 ± 1.12 cm s^-1 mmHg^-1) during TGS, after the α-blockade CBV (Δ0.98 ± cm s^-1) and CVCi (Δ-0.03 ± 0.06 cm s^-1 mmHg^-1) response to TGS did not change.

Conclusion: Coronary circulation increases during sympathetic stimulation even with a decrease in heart rate.

Keywords: Blood velocity; Circulation; Coronary; Trigeminal nerve.