The Influence of Reserpine on the Intracellular Distribution of Noradrenaline in the Rat Heart

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Abstract
Rats, exposed to a cold stress or treated with a low dose of reserpine, were killed at various times and their hearts removed and homogenized in phosphate buffer. Subsequent centrifugation of the homogenate produced three fractions 1) a coarse fraction following low speed centrifugation 2) a particulate fraction and 3) a supernatant fraction obtained by high speed centrifugation of the first supernatant. These 3 fractions plus aliquots of the total homogenates were assayed for noradrenaline content. Following reserpine, 0.1 mg/kg, a preferential fall in the noradrenaline concentration in the supernatant fraction occurred after 1 hour, without any fall in the noradrenaline content of the particulate fraction. Two hours after reserpine the total noradrenaline content was reduced to about one‐half, with the same relative proportion of amines in the particulate fraction and in the supernatant as after 1 hour. Cold stress, inducing a strong increase in noradrenaline release, failed to alter either the total noradrenaline content of the hearts or the intracellular distribution of this cate‐cholamine. It is suggested that the amine fall in the supernatant fraction after reserpine results from an impairment in the release of noradrenaline from the particulate fraction.