Histochemical fluorescence studies on noradrenaline accumulation by Uptake2in the isolated rat heart

Abstract

1 . The distribution of noradrenaline accumulated by Uptake₂ (Iversen, 1965) in the isolated perfused rat heart has been observed using histochemical fluorescence microscopy. 2 . On the basis of the technique used, noradrenaline seems to be predominantly associated with the cardiac muscle cells, but sympathetic nerves and other cardiac structures also serve as retention sites. 3 . Phenoxybenzamine, normetanephrine and perfusion with noradrenaline at 20° C all decreased noradrenaline accumulation. 4 . Lowered temperature significantly increased the perfusion pressure and significantly decreased the [¹⁴C]-sorbitol space in perfused hearts. 5 . The implications of these results are discussed.