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The development of heart failure in the cardiomyopathic hamster is associated with a decrease in norepinephrine stores and parallel increases in cardiac sympathetic tone and tyrosine hydroxylase activity. Despite the increase in tyrosine hydroxylase, cardiac norepinephrine synthesis does not increase in heart failure. In this study, we have shown that an accumulation of cardiac dopamine accompanies the decline of cardiac norepinephrine. The abnormal content of norepinephrine and of dopamine in the decompensating hamster heart is restored to normal by peripheral ganglionic blockade. The acute increase in cardiac sympathetic tone induced by immobilization stress in control hamsters mimics the alterations in cardiac catecholamine distribution found in heart failure. Other investigators have demonstrated similar alterations in the catecholamine content of the rat submaxillary gland and adrenal medulla following an increase in sympathetic input to these organs. We conclude that the increase in cardiac sympathetic tone in the late stages of hamster cardiomyopathy appears to lead to a shift in the rate-limiting step for norepinephrine synthesis from the hydroxylation of tyrosine to the hydroxylation of dopamine. There is evidence that this shift which results in an accumulation of dopamine in the noradrenergic nerve terminals of the heart is a general manifestaion of augmented sympathetic nerve traffic rather than a peculiarity of hamster cardiomyopathy.

The effect of a direct-current electric field on cephalin and lecithin films was measured using infrared spectral techniques. The intensities of the spectral bands assigned to the vibrations of the phosphate and the fatty acid chain increased to a maximum as the applied potential was increased. These changes were observed only with brain cephalin and brain lecithin films and not with synthetic lipid films. These observations may be due to changes in the alignments of the phosphate and base dipoles in the lipid molecule as the applied field is changed. The electric field strengths at which the maximum intensities of the spectral bands are observed increase as the thickness decreases. Extrapolation to the thickness of the nerve membrane yields a value of the field strength that is much larger than is to be expected in the neuron. This suggests that only the phosphate group and the hydrocarbon chain change conformation during the passage of the nerve impulse.

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