Cold exposure increases cyclic guanosine monophosphate in healthy women but not in women with Raynaud's phenomenon

Abstract

Objective: To investigate influence of whole-body cooling on cyclic GMP (cGMP) in women with Raynaud's phenomenon and in healthy women.

Design: The study was performed as an open, parallel-group comparison between women with Raynaud's phenomenon and healthy women during the winter month of February.

Setting: The municipality of Västerås (Sweden).

Participants: The Raynaud group comprised 24 female patients. The control group consisted of 21 healthy females.

Main outcome measure: The venous levels of cGMP were measured on three different occasions: just before and after 40 min of whole-body cooling and after 20 min rest at room temperature (21 degrees C).

Results: Venous cGMP increased significantly in the control group after cold exposure (mean difference 0.43 pmol mL-1; 95% CI, 0.018-0.848; t = 2.18; df = 20; P = 0.02) and remained at a high level after 20 min rest (mean difference 0.58 pmol mL-1; 95% CI, 0.063-1.108; t = 2.34; df = 20; P = 0.015). In contrast, the levels of venous cGMP in the Raynaud group did not change significantly. The difference in increase between the two groups was significant (P < 0.02). The diastolic blood pressure in the Raynaud group increased after 40 min of whole-body cooling and was still significantly increased (P < 0.001) after 20 min rest at room temperature (21 degrees C).

Conclusion: These results indicate that women suffering from Raynaud's phenomenon lack the physiological response of cGMP to cold exposure, which may explain their increased vasospastic response.