A comparison of rates of depletion and recovery of noradrenaline stores of peripheral and central noradrenergic neurones after reserpine administration: importance of neuronal activity

摘要

>1 The noradrenaline (NA) content of various peripheral sympathetic neuroeffector organs and brain was measured at various times after different doses of reserpine administered to the rat.>2 About a 25% reduction in the NA content of the heart was observed 24 h after 0.005 mg/kg reserpine. Two to ten times more reserpine was needed to obtain an approximately similar degree of depletion in the salivary gland and vas deferens; 0.1 mg/kg produced almost complete depletion in the heart and salivary gland, whereas 5 mg/kg was needed to deplete the vas deferens of its NA content.>3 The NA content of the brain and superior cervical ganglion was lowered by 20 to 30% in 24 h only when the reserpine dose was raised to 0.1 mg/kg, and 5 to 10 mg/kg was required to obtain over 95% depletion.>4 The rates of recovery of cardiac and salivary gland NA stores, after about 80 to 100% depletion by low and high doses of reserpine, were almost identical. About 50% restoration occurred in 7 to 15 days after a single dose of 0.1 mg/kg reserpine.>5 The superior cervical ganglion, the NA content of which was fully depleted by 10 mg/kg, showed almost complete recovery in about 7 days.>6 Transmural stimulation of the left atrium of the guinea-pig for 30 min (5 Hz for 30 s/min), or exposure of the atrium to reserpine (5 μg/ml) for 30 min, caused modest but statistically insignificant reduction in tissue NA content. However, stimulation in the presence of reserpine 5 μg/ml for 30 min produced about 50% depletion of NA.>7 In vitro reduction in NA content caused by reserpine plus transmural stimulation, was even more pronounced after treatment of the isolated vas deferens of the rat with tetraethylammonium.>8 It is suggested that different rates of depletion following in vivo administration of reserpine are mainly due to variation in neuronal activity of different sympathetic neuroeffector organs.