Microcirculatory vasoconstrictor response: relationship with vital capacity and smoking

Vasoconstrictor response (VR) induced by inspiratory gasp exhibited a strong positive correlation with vital capacity (VC) which reflects the magnitude of the input stimulus for VR (Lau et al., Clin. Sci. 89:233-237, 1995). Whether a stoichiometric relationship existed between VC and VR is not known. We examined this question in two studies by determining VC and microcirculatory blood flow with laser Doppler flowmetry in healthy subjects. We first studied 40 non-smokers of different gender and age and found that the variation in VR cannot be eliminated by normalization with VC. In the second study we examined 10 young male smokers as well as matched non-smokers of identical VC, we found that smokers had reduced VR. Taking together, the present studies demonstrated that vasoconstrictor response (VR) was not determined by vital capacity alone and that smoking adversely affected VR in the absence of altered VC.