Heart rate-dependence of arterial distensibility in vivo

Objectives Viscous and inertial components contribute to arterial distensibility and compliance in vitro. The purpose of our study was to determine whether this phenomenon is of relevance in vivo, namely, whether arterial compliance is altered by an increase in heart rate. Design Arterial diameter was assessed by an echo-Doppler device in a common carotid and femoral artery, namely, in a large elastic and a muscle artery. The studies were performed in 12-week-old pentobarbitone-anaesthetized Wistar-Kyoto rats subjected to atrial pacing via a transjugular unipolar catheter at five different randomly sequenced rates (280, 310, 340, 370 and 400 beats/min). After each stage, spontaneous sinus rhythm was allowed to return. Blood pressure was measured via a catheter inserted into the carotid or femoral artery contralateral to the vessels in which the diameter was measured. Arterial compliance and distensibility values were derived according to the Langewouters formula. Results A progressive ...