Abstract
Ethanolic phosphotungstic acid (EPTA) method and G-6-Pase method were used to localize cytochemically the atrial specific granules (ASG) and sarcoplasmic reticulum (SR) of rat atrial cardiocytes under the electron microscope, and at the same time, the calcium (Ca) in ASG and SR was analyzed quantitatively by analytical electron microscopy (AEM). In these methods, the procedure of osmium tetroxide fixation was shortened or even abolished to keep more combined Ca. The Ca concentration in ASG and in the terminal cisterns of SR (TSR) was 64±16 and 99±21mM/kg dry wt respectively. These values are approximate to those reported in earlier works that were done on cryosections. It is suggested that these cytochemical methods could reserve a large part of combined Ca in the intracellular Ca store, and they are much simpler than the low temperature techniques of biological specimen preparation. Therefore, these methods are useful for AEM microanalysis of elements in organelles.
