Female-specific echocardiography-derived cardiac responses to the cold pressor test

We previously demonstrated heterogeneous vascular resistance (VR) responses to the cold pressor test (CPT) in females. Since cardiac output (CO) is a key determinant of the pressor response, we prospectively examined cardiac contributions to the CPT, hypothesizing that females would exhibit heterogeneous cardiac and vascular responses to the CPT. Nineteen healthy females (24 ± 3 yr, body mass index 22.9 ± 1.9 kg/m²) and a comparator group of nine males (23 ± 3 yr, 24.8 ± 1.6 kg/m²) completed a 3-min CPT including continuous measurements of mean arterial pressure (MAP; finger photoplethysmography), CO [stroke volume (SV) (echocardiogram) × heart rate (HR) (3-lead electrocardiogram)], and femoral VR [FVR; MAP/femoral blood flow (duplex ultrasound)]. The magnitudes of CPT-induced changes (Δ) in MAP (P = 0.96), HR (P = 0.59), CO (P = 0.09), and %FVR (P = 0.46) were not different between sexes; ΔSV was smaller in females (1.0 ± 5.0 vs. 5.0 ± 3.0 mL, P = 0.03). ΔSV responses were distinctly heterogeneous in female participants; females demonstrating positive ΔSV (SV_INC; n = 10) and negative ΔSV (SV_DEC; n = 9) were subdivided for subsequent analyses. SV_INC had higher ΔSV (5.0 ± 3.0 vs. -3.0 ± 2.0 mL; P < 0.001; by design) and ΔCO (1.11 ± 0.48 vs. 0.47 ± 0.43 L/min; P = 0.01) but lower Δtotal peripheral resistance (TPR) (median: -2 [interquartile range (IQR): 3] vs. 1 [2] mmHg/L/min; P = 0.008). %FVR (P = 0.87), ΔHR (P = 0.13), and ΔMAP (P = 0.85) did not differ between subgroups. Among all females, ΔSV was positively associated with ΔCO and negatively associated with ΔTPR but not ΔFVR, ΔHR, or ΔMAP, indicating that heterogeneous SV responses in females may be offset by systemic vascular resistance responses and do not impact the overall magnitude of the pressor response to the CPT.NEW & NOTEWORTHY Sex-specific cardiac and vascular cold pressor test (CPT) responses have not been well described. In females, we observed bidirectional CPT-induced, echocardiography-derived stroke volume (SV) responses that were negatively correlated with total peripheral resistance but not blood pressure, whereas males consistently increased SV. Pressor responses did not differ between sexes. These data support interindividual heterogeneity in the mechanisms by which females respond hemodynamically to the CPT, which do not appear to influence pressor responses.