A method is described for isolating purified nuclei from rat heart and kidney and RNA polymerase has been measured in Mg2+, KG and Mn2+, (NH2SO* media of relatively low ionic strength. Two weeks following adrenalectomy, in heart nuclei, Mg2+-activated RNA polymerase had fallen to 60% and the Mn2+- activated enzyme to 77% of sham-operated ’normal’ values. In kidney nuclei the Mg2+-activated enzyme fell to 68% and the Mn2+-activated enzyme to 69% of normal values. Following administration of aldosterone (5 per 100 g) to adrenalectomized rats the Mg2+-activated RNA polymerase, in heart nuclei, increased in 2-3 hours to 105% and the Mn2+-activated enzyme to 123% of normal values. In kidney nuclei from adrenalectomized rats no effect was seen for two hours after aldosterone administration, but by 3 hours the Mg2+-activated enzyme was restored to 117% and the Mn2+-activated enzyme to 107% of normal values. Corticosterone (250 n-g per 100 g) had no effect on heart or kidney RNA polymerase activity in adrenalectomized rats. Aldosterone had no significant effect on Mg2+- activated RNA polymerase of liver nuclei from adrenalectomized rats but increased the Mn2+- activated enzyme to 150% of adrenalectomy values. No effect of aldosterone was demonstrated on RNA polymerase activities of heart or kidney nuclei in vitro. (Endocrinology90: 488, 1972)
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Liew et al. (1972) studied this question.