BACKGROUND: The cold pressor test (CPT) is widely used sympathoexcitatory stimulus, and CPT responses are known to be exaggerated in individuals with hypertension and diabetes. Surprisingly, however, the hemodynamic responses to the CPT have not been explicitly characterized in individuals with metabolic syndrome (MetS). Hence, the purpose of this study was to characterize the hemodynamic responses to cold pressor activation in individuals meeting the criteria for MetS. METHODS: 75 individuals were initially screened for MetS based on the National Cholesterol Education Program Adult Treatment Panel III criteria, with the addition of HbA1C >5.7% as a secondary marker of impaired glucose regulation. Of these 75 participants, 20 met the criteria for MetS, 17 completed all experiments and could be matched to control participants by age, biological sex, race, and ethnicity. Upon final analysis, one participant was excluded as an outlier (mean pressor response >3.5 standard deviations above the inclusive group mean), resulting in a final matched comparison of 16 individuals with MetS and 16 control participants. Each CPT consisted of a 2-minute baseline period, followed by a 2-minute period of ice-water hand immersion, during which heart rate and beat-by-beat blood pressure were continuously recorded via a one-lead electrocardiogram and finger-photoplethysmography, respectively. CPT responses were quantified as the peak blood pressure and heart rate responses recorded during cold-water immersion, as well as the area-under-the-curve for mean arterial pressure (MAP) during cold-water immersion (BPI; mmHg*sec). RESULTS: As expected, individuals with MetS had a significantly higher BMI (p=0.001), waist circumference (p<0.001), fasting blood glucose (p<0.001), resting systolic blood pressure (p=0.01), resting diastolic blood pressure (p=0.008), and lower HDL cholesterol (p=0.006) compared to control participants. However, the only significant difference observed during the CPT was an exaggerated peak diastolic blood pressure response in the MetS group (p=0.045). In contrast, no significant differences were observed for the peak MAP (p=0.104), delta MAP (p=0.859), or BPI responses (p=0.114). CONCLUSIONS: Based on these findings, only diastolic blood pressure responses are exaggerated during cold pressure activation in individuals with MetS, whereas systolic, MAP, and HR response are similar between groups.

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