Combined quantitative morphological and biochemical study on atrial granules (AG)

Abstract

The first morphological study concerning the endocrine heart was published by Kisch (12) who had detected a peculiar cytoplasmic inclusion body in muscle cells of the guinea-pig atrium. Only a few years later, Jamieson and Palade (11) described that these structures were specific granules occuring in all mammalian species investigated, including man. Twelve years later, Marie et al. (13) analysed morphometrically the interference between the number of atrial granules and changes in salt and water balance. Recently, DeBold et al. (4) proved the natriuretic and diuretic properties of atrial extracts and postulated a new class of hormones, which are now known as the atrial natriuretic polypeptides (ANP). Further biological activities were detected, namely the vasorelaxant effect of atrial extracts (3,6). This vasorelaxant function is based on the polypeptide hormone, atriopeptin or cardiodilatin (CDD). It is now well known that the different polypeptides characterized in 1983 and 1984 are all expressed from the same gene and present as posttranslational or artificial cleavage products (2,7). In contrast to the large number of biochemical, physiological investigations, and morphological studies on cardiac hormones published so far, combined morphometric and biochemical studies are not available. Exact data based on both stereological-ultrastructural and radio-immunological examination of the endocrine heart, however, is of major importance for the understanding of the secretory activity of myoendocrine cells.