Adrenergic Control of the Cutaneous Circulation during Cryotherapy

Abstract

Cryotherapy application is a widely clinically used therapeutic technique using ice or cold water applied to the skin surface to reduce local blood flow. While beneficial, cryotherapy treatment does have the potential to induce some detrimental physiological side effects. For example, cryotherapy treatment induces pronounced tissue ischemia that is sustained for hours even during a post-treatment rewarming period. PURPOSE: To investigate the role of adrenergic receptor activation on cutaneous blood flow during 30 min of cryotherapy as well as during the subsequent 1 hr of passive rewarming. We hypothesized that adrenergic-mediated vasoconstriction is involved in pronounced and sustained cutaneous vasoconstriction that occurs during cooling and passive rewarming. METHODS: To date 4 complete data sets have been collected with 2 partial, incomplete datasets. A commercially available cryotherapy unit with a water perfused bladder was used. The bladder was placed on the lateral portion of the calf. Four microdialysis membranes were threaded through the dermis of the skin directly underneath the water bladder. One site was perfused with lactated ringers solution (CON), one with bretylium tosylate (BRE), one with propranolol+yohimbine+BIBP (PBY), and one with propranolol+BIBP (PB). Skin temperature (SkT) and skin vascular conductance (SkVC) was measured at each site. Subjects had 0 °C water perfused through the cryotherapy bladder for 30 min, followed by passive rewarming (i.e. water shut off) for 1 hr, followed by direct heating with 46 °C for 10 min. RESULTS: SkT fell from 33°C to 17.7°C during 30 min of cold water application across all sites. SkVC at CON was reduced ∼80% after 30 min of cooling and was not significantly different than PB (p>0.05). Vasoconstriction was attenuated at the BRE and PBY sites during cooling compared the control (SkVC: BRE = 58% reduction, PBY = 37% reduction, CON 80% reduction (p<0.05 for each comparison). Following 10 min of active warming the BRE site was not different than CON (SkBF: 46% reduction vs. 28% reduction (P>0.05). CONCLUSION: Our preliminary finding was that adrenergic function mediates the vasoconstriction that occurs with cryotherapy application. This is in line with previous literature investigating the adrenergic mechanisms of vasoconstriction with skin cooling.