The Relative Density of Sympathetic Nerve Terminals in the Canine Right Atrium 1

Abstract

Summary

Relative densities of sympathetic nerve terminals in 20 consecutive sections of both normally innervated (n = 10) and chronically denervated (n = 8) dog right atria were determined by comparative uptakes of [³H]norepinephrine. Results of analysis of neurally intact atria display a consistent gradient of [³H]norepinephrine with the highest concentration (130,000 dpm/g) in the tip of the atrial appendage and the lowest (30,000 dpm/g) in the - trial septum. The region containing the SA node was not distinguished by significantly high uptake. Atria of chronically dener-vated hearts had a markedly diminished [³H]norepinephrine uptake (average of 28,000 dpm/g). No gradient of radioactivity between sections was present in the dener-vated atria. These results indicate that (1) the canine right atrium has marked concentrations of sympathetic terminals in the appendage, (2) the technique of [³H]-norepinephrine uptake gives a quantitative evaluation of sympathetic nerve terminal density, and (3) the technique allows for evaluation of the status of cardiac denervation.