Calcitonin gene-related peptide, neuropeptide Y and atrial natriuretic peptide distribution in guinea pig heart from paraffin wax-embedded and formalin-cryoprotected tissues

In this study, the distributions of calcitonin gene-related peptide, neurop eptide Y, and alpha-atrial natriuretic peptide 1-28 immunoreactivity, were investigated within different regions of the guinea pig heart by utilising two different methods of tissue fixation for the immunocytochemistry. The r esults were compared with data obtained through radioimmunoassays. We obser ved similar concentrations and distributions of alpha-atrial natriuretic pe ptide in the right atrium, with results of radioimmunoassay and immunocytoc hemistry, but there were no myocytes containing alpha-atrial natriuretic pe ptide in the left atrium or ventricles with immunocytochemistry as opposed to radioimmunoassay. The immunoreaction obtained for neuropeptide Y was mor e intense in the right ventricle than left. Calcitonin gene-related peptide nerve fibres were about twice as abundant in the left atrium than in the r ight.