Immunocytochemical localization of atrial natriuretic factor in the heart and salivary glands

Abstract

Antibodies produced in the mouse by repeated intraperitoneal injections of partly purified atrial natriuretic factor (low molecular weight peptide (LMWP) and high molecular weight peptide (HMWP)) have been used to localize these factors by immunohistochemistry (immunofluorescence and immunoperoxidase method) and by immunocytochemistry (protein A-gold technique) in the heart of rats and of a variety of animal species including man and in the rat salivary glands. Immunofluorescence and the immunoperoxidase method gave identical results; in the rat, atrial cardiocytes gave a positive reaction at both nuclear poles while ventricular cardiocytes were consistently negative. The cardiocytes of the right atrial appendage were more intensely reactive than those localized in the left appendage. A decreasing gradient of intensity was observed from the subpericardial to the subendocardial cardiocytes. The cardiocytes of the interatrial septum were only lightly granulated. Sodium deficiency and thirst (deprivation of drinking water for 5 days) produced, as already shown at the ultrastructural level, a marked increase in the reactivity of all cardiocytes from both atria with the same gradient of intensity as in control animals. Cross-reactivity of intragranular peptides with the rat antibodies allowed visualization of specific granules in a variety of animal species (mouse, guinea pig, rabbit, rat, dog) and in human atrial appendages. No reaction could be elicited in the frog atrium and ventricle although, in this species, specific granules have been shown to be present by electron microscopy in all cardiac chambers. With the protein A-gold technique, at the ultrastructural level, single labeling (use of one antibody on one face of a fine section) or double labeling (use of two antibodies on the two faces of a fine section) showed that the two peptides are localized simultaneously in all three types (A, B and D) of specific granules. In the rat salivary glands, immunofluorescence and the immunoperoxidase method showed reactivity exclusively in the acinar cells. The reaction was most intense in the acinar cells of the parotid gland. In the sublingual gland, only the serous cells, sometimes forming abortive "demi-lunes", were reactive. In the submaxillary gland, the reaction was weaker and distributed seemingly haphazardly in the gland. The most constantly reactive cells were localized near the capsule while many cells did not contain visible reaction product.

Atrial Natriuretic Peptide presence in parotid gland of human fetus at 13th week of development and in adult man

“…The ANP presence in the ducts was probably related to the natriuretic activity of ANP, since saliva is an ion-rich fluid which content becomes modified during passage along the ductal epithelium in both intra-and extralobular ducts, where most of the NaCl is being reabsorbed [31]. Furthermore ANP in human parotid gland has the same localization as in rat [8,10] and rabbit [12].…”

“…Cantin et al [8] found that in rat parotid gland ANP immunoreactivity was intense exclusively in the acinar cells; in sublingual gland only the serous cells were immunoreactive, whereas in submaxillary gland the reaction was weaker and distributed randomly in the gland. By contrast, Gutkowska and Nemer [9] found the ANF-immunoreactivity confined to the granular convoluted tubular cells of the submaxillary gland.…”

Myocardial lesions and the alteration of atrial granularity in dystrophic mice.

“…Recent use of the protein A-gold immunocytochemical technique has made apparent the atrial natriuretic polypeptide (ANP), which possesses potent diuretic, natriuretic and vasorelaxant activities and is localized in the specific atrial granules (DE BOLD et al, 1981;CANTIN et al, 1984). The granularity of the atrial cells has been known to alter in some experimentally induced water-electrolyte imbalances (MARTINEZ-P. and BENCOSME, 1966;CANTIN and HUET, 1973;DE BOLD, 1979).…”

Fine Structure of the Atrial Cardiocytes in the House Musk Shrew (<I>Suncus murinus</I>)

“…Several investigators have used immunohistochemical techniques to study the distribution of ANP and ANP-related peptides (cardiodilatin, atrial natriuretic factors, atriopeptin II) in mammalian hearts [2,4,7,8,10]. They have described that the most intensely granulated cardiocytes are located in the auricle and that the number of densely granulated cells is greater in the right atrium than in the left.…”