Poiseuille, periodicity, and perfusion: rhythmic oscillatory vasomotion in the skin

Cutaneous vasomotion has not been actively investigated until recently. This is hardly surprising, as it has not been a reproducible phenomenon. During recent studies on various physiological and pharmacological vascular problems, we identified experimental conditions in which cutaneous vasomotion commonly occurred. We then characterized four methods that routinely provoke human cutaneous vasomotion in vivo, in order to further characterize this physiological phenomenon. Although several adaptive advantages may exist for vasomotion, the most compelling theory can be derived mathematically from Poiseuille's law. Because the flow of a liquid through a vessel is proportional to the fourth power of the radius, it can be demonstrated that the resistance of a vessel with a constant diameter is greater than that of a vessel of the same average diameter in which the diameter changes sinusoidally. Importantly, the rhythmicity originates within the vascular tissue, and there appears to be electromechanical coupling. The cation effluxes demonstrate oscillatory behavior that may be driven by the availability of adenosine triphosphate. Substrate and product concentrations can alter the activity of the allosteric enzyme, phosphofructokinase, which may control the oscillations in ATP concentration. Despite the qualitatively different provocative agents, the cutaneous rhythmic oscillatory vasomotion always first appears after a peak in erythrocyte flux, and it disappears before reaching resting flux levels. Thus, cutaneous rhythmic oscillatory vasomotion is a midrange phenomenon, most likely corresponding to the "oscillatory domain" of glycolysis. Finally, a common feature of tissue preparations for the study of vasomotion is that anesthesia was not used. We have shown that this inhibitory effect of anesthetic agents may persist well beyond "anesthesia," and this suppression may be of clinical importance in the patient with microcirculatory compromise undergoing surgery.