The associations between cardiovascular and pain responses to a cold pressor test differ between males and females.

Abstract

Nociceptors contribute to the cardiovascular responses during a cold pressor test (CPT). While these responses are lower in females, data suggest that they perceive the CPT as more painful. Thus, we examined sex differences in associations between pain and cardiovascular responses to a CPT (Aim 1) as well as differences between females using (OC), and not using (NC), an oral contraceptive (Aim 2). 25 males (23 ± 5 years) and 25 females (21 ± 3 years; 11OC and 14NC) were studied. Cardiovascular data and pain levels (0-10 scale) were recorded at baseline then during a two-minute CPT; changes from baseline to peak response were analyzed. Systolic blood pressure (SBP, p = 0.57), mean arterial pressure (MAP, p = 0.22), heart rate (HR, p = 0.58), and pain (p = 0.71) responses did not differ between sexes; diastolic blood pressure (DBP) increased more in males (17 ± 8 vs. 13 ± 6 mmHg, p < 0.05). Pain was associated with HR in males (r = 0.42, p < 0.05) but not females (r = -0.16, p = 0.44); no other associations were observed in either sex (p = 0.48-0.92). SBP (27 ± 12 vs. 15 ± 6 mmHg), DBP (16 ± 6 vs. 9 ± 5 mmHg), MAP (20 ± 7 vs. 14 ± 5 mmHg), and HR (8 ± 5 vs. 2 ± 5 beats/min) were greater in NC than OC (p < 0.05 for all); pain was similar (p = 0.38). In NC, pain was associated with DBP (r = 0.65, p = 0.01) and MAP (r = 0.65, p = 0.01), but not HR (r = -0.43, p = 0.13), and tended to be associated with SBP (r = 0.46, p = 0.09). In OC, pain was inversely associated with SBP (r = -0.62, p < 0.05) but no other outcome (p = 0.40-0.65). We report a sexual dimorphism in the HR-pain association during a CPT and underscore the impact of oral contraceptives.