Abstract

The cold pressor test (CPT) has been long used as an activator of the sympathetic nervous system (SNS) but it is not clear if the CPT consistently results in the increases in salivary α-amylase (sAA), and how the changes in salivary α-amylase are correlated to cardiovascular and hemodynamic parameters. Additionally it is not known how individuals can be characterized based on these correlations.

30 healthy participants, 14 males and 16 females, underwent a hand CPT for 5 minutes at 4°C while having their cardiovascular and hemodynamic parameters monitored and saliva sampled. The CPT resulted in changes in most cardiovascular and hemodynamic parameters measured, SBP, DBP, MAP, TPR, PEP, LVET, PEP/LVET, dP/dt, and dZ/dtmax. There was no significant change in HR, CO, and SV. The CPT caused an increase in salivary α-amylase at the end of the 5 minutes, that continued to increase up to 10 minutes post CPT. The change in magnitude (Δ) of Δ1 sAA or Δ2 sAA was correlated to the Δ1HR (ρ=0.5, p<0.01) (ρ=0.48, p<0.05) respectively. CPT sAA levels were correlated to baseline HR (ρ=0.43, p<0.05) and inversely proportional to Δ1SBP (ρ=-0.47,p<0.01) and baseline PEP (ρ=-0.38, p<0.05).When grouped based on high (<20mmHg) or low (>20mmHg) systolic response to the CPT, low responders had higher resting salivary α-amylase and higher resting HR than the high responders suggesting that SNS activity can be characterized using the CPT and salivary α-amylase measures. While the CPT caused robust changes in salivary α-amylase, the delayed increase suggests that other measures such as ΔSBP are better indicators of the SNS response in healthy people.