Effects of 7 drugs on cutaneous blood flow evoked by electric stimulation of rat sciatic nerve

The non-invasive technique of laser-Doppler flowmeter (LDF) was used to measure the change of cutaneous blood flow evoked by electric stimulation of rat sciatic nerve. The sciatic nerve was cut centrally and placed on bipolar electrodes. Drug were infused in a carotid artery. Electric stimulation of the sciatic nerve containing sensory afferent fibers caused an increase in cutaneous blood flow. This increase was not modified by the ia infusion of adrenergic blocking agents (phentolamine, 0.1 mg/kg and propranolol, 0.5 mg/kg), anti-muscarinic agent (atropine 0.5 mg/kg), anti-histamines (mepyramine, 10 mg/kg and cimetidine, 10 mg/kg) and 5-HT antagonist (methysergide, 0.5 mg/kg). Pretreatment with capsaicin (50 mg/kg, sc) in the newborn rat or the ia infusion of spantide (1, 2 mumol/kg) significantly inhibited the the stimulation-induced increase of the blood flow. These results suggest that substance P released from the peripheral endings of sensory nerve may be involved in vasodilation following electric stimulation of the sciatic nerve in rat.