“…Thus, ^-receptor-mediated alterations in tubular sodium and fluid reabsorption (e.g., Kim et al, 1979) might be due to humoral and not neurally released catecholamines. In particular, the apparent predominance of ft-adrenergic receptors in tubules and in medullary locations in our studies, and of /^-receptors in cultured renal tubular cells (Meier et al, 1983;Simmons et al, 1984), suggests the potential importance of circulating epinephrine (which is more potent at /92-adrenergic receptors than norepinephrine) in the activation of 0 2 -receptors to alter tubular reabsorption of sodium and water. This activation might particularly come into play under conditions (e.g., stress, exercise, shock) in which epinephrine levels are elevated.…”