Atriopeptin does not augment the transvascular flux of macromolecules in the hamster cheek pouch

AbstractNatriuretic peptides elaborated by atrial myocytes promote marked renal sodium and water excretion as a mechanism for fluid and electrolyte balance. Recent evidence suggests that atriopeptin (ANP) also targets the nonrenal vasculature as a site for enhanced fluid exchange. It remains unclear whether ANP alters microvascular integrity to facilitate the efflux of both plasma and proteins across the endothelial barrier, or if fluid exchange is selectively enhanced. This study evaluated the influence of ANP on macromolecular transport through the direct observation of microvessels in the hamster cheek pouch using fluorescent intravital microscopy. Fluorescein isothiocyanate conjugated to either bovine serum albumin or dextran 150,000 Mw was utilized as a permeability probe. Macromolecular efflux was quantified as fluorochrome clearance. The clearance of fluoresce in conjugted bovine serum albumin (57.94 ± 7.03) or fluorescein-conjugated dextran 150 (4.09 ± 1.35) remained unaltered by intravascular inj...