Sex and menstrual cycle effects on cerebrovascular responses to a single foot cold pressor test

The cold pressor test (CPT) involves cold water immersion of upper or lower limb(s) to elicit hemodynamic responses and can be used as a stimulus for understanding sex differences in vascular regulation. Limited research exists on understanding cerebrovascular responses to CPT, though previous work suggests males have higher levels of common carotid artery (CCA) dilation than females during CPT. Additionally, it is unclear whether menstrual cycle phase or use of exogenous hormones affect the CPT response in females. This study aimed to assess how the CCA responds to the CPT in males versus females who are not using exogenous hormones, and whether menstrual cycle phase impacts the CCA responses to CPT in females. Cerebral and systemic hemodynamics were assessed during a 3-minute single foot CPT in 33 young healthy adults (16 males - 1 visit, 17 females - 2 visits: early-follicular [EF] and mid-luteal [ML] menstrual cycle phases). Mean arterial blood pressure (MAP), middle cerebral artery blood velocity (MCAv) and conductance index (MCACVC), end-tidal carbon dioxide (PETCO2), CCA diameter, blood velocity, flow, and conductance, MCA and CCA pulsatility, and cerebral damping were measured at baseline and at each minute of the CPT protocol. CCA diameter, flow, and conductance were higher in males than in females during EF and ML, and females in ML had greater decreases in MCA pulsatility and greater increases in damping than males. Cerebrovascular hemodynamic responses to a single foot CPT in young adults are not different between early follicular and mid-luteal phases of the menstrual cycle.