Aspects of the Difference in Vascular ‘Reactivity’ between Cutaneous Resistance Vessels and A-V Anastomoses

Abstract

The aim of the present study on cats has been to illustrate in model experiments the hemodynamic importance of an increased wall/lumen ratio. A comparison was made between cutaneous A-V shunts and nutritional resistance vessels with respect to threshold and suprathreshold noradrenaline responses and to graded vasoconstrictor fiber stimulations. No significant difference in smooth muscle sensitivity was observed between the 2 sets of cutaneous vessels studied. However, in keeping with the higher wall/ lumen ratio of the A-V shunts they exhibited an increased reactivity to stepwise increases of suprathreshold stimuli, insofar as their luminal reductions became increasingly exaggerated compared with those of the nutritional resistance vessels.