X-ray microanalysis of isolated perfused rat hearts.

X-ray microanalysis was carried out on sections from isolated hearts perfused with a modified Krebs-Henseleit solution with or without isoproterenol. Changes in P, Ca and Zn concentrations could be detected after isoproterenol and some correlation with hemodynamic and morphological parameters was observed. Ratios between P/Ca in myonuclei and the ratios of interstitial cell to myofiber nucleus calcium were related directly to the state of the heart.