No abstract

Freshly prepared duck erythrocytes, incubated either in plasma or an isotonic synthetic medium containing norepinephrine ([K] of both media 2.5 m), maintain water and electrolyte composition in the steady state (upper steady state) for at least 90 min. If incubated in the synthetic medium without norepinephrine or in plasma to which a -adrenergic blocking agent (propranolol) is added, the cells lose both water and electrolyte (predominantly KCI) until a new steady state is reached (lower steady state). Reaccumulation of water and electrolyte from isotonic solutions toward the upper steady-state levels requires the addition of norepinephrine and KCI. Reaccumulation is maximal when the concentration of K and norepinephrine in the medium is 15 mM and 10-7 M, respectively. Dibutyryl cyclic-AMP (10-2 M) mimics norepinephrine in lower steady-state cells. Although an analogous effect in upper steady-state cells was not established with certainty, it is proposed that the catecholamine-induced net changes in water and electrolyte movement in duck erythrocytes are a consequence of stimulation of the activity of a membrane-bound adenyl cyclase system.

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