Factors affecting the permeability of isolated fat-cells from the rat to [42K]potassium and [36Cl]chloride ions

[摘要]

1. The effluxes of ⁴²K⁺ and ³⁶Cl⁻ from isolated fat-cells from the rat were studied under a variety of conditions known to affect the metabolism of the cells. 2. ⁴²K⁺ efflux from isolated fat cells was increased in a Na⁺-free–high-K⁺ medium and decreased in a K⁺-free medium. The existence of K⁺ exchange diffusion across the fat-cell membrane is suggested. 3. ³⁶Cl⁻ efflux from isolated fat-cells was decreased when the Cl⁻ component of the wash medium was replaced by acetate. The basal ³⁶Cl⁻ efflux is suggested to be partly by Cl⁻ exchange diffusion and partly in company with a univalent cation. 4. A variety of lipolytic stimuli, adrenaline, adrenocorticotrophic hormone, N-6,O-2′-dibutyryladenosine cyclic 3′:5′-monophosphate and theophylline, increased ⁴²K⁺ efflux from isolated fat-cells. The adrenaline stimulation was biphasic; an initial, rapid and transient increase in ⁴²K⁺ loss from the fat-cells was followed by a slower, more prolonged, increase in ⁴²K⁺ efflux. The initial phase was inhibited by phentolamine but not by propranolol. 5. Insulin increased ⁴²K⁺ efflux only after preincubation with the cells.