Electrofusion of rat adrenal and Leydig cells generated hybrids capable of synthesizing simultaneously both testosterone and corticosterone, under stimulation of lutropin or adrenocorticotropin. Evidence was obtained indicating that under such circumstances, heterologous lutropin receptor -adrenal adenylate cyclase complexes were formed.Cell fusion has a great importance in the generation of heterocarions and hybrid cell lines [I -31. The technique has also been used to study the mobility of cell membrane markers and receptors [4, 51. Fusion of cells, in homogenous or heterogenous populations, is achieved in vitro by treating cell suspensions with inactivated sendai virus, poly(ethy1ene glycol) or lysophosphatidylcholine [2, 6-81. A main limitation of these 'fusogenic agents' is however, the low yield and the scarce viability of the hybrids thus obtained.Electrical-field-induced cell fusion has been recently proposed as an alternative to the use of the above-mentioned fusogenic agents [9 -111. The technique involves the orientation of cells under an asymmetric, alternating current field, a phenomenon called dielectrophoresis [I 2 -171 and the induction of the fusion process by an electrical breakdown pulse [9 -111. Evidence indicates that, with such a fusion procedure, yields of viable hybrids are several orders of magnitude higher than with methods using chemical fusogenic agents [9, 101. Since the electrofusion procedure has been only recently introduced to studies on animal cells [lo], there is not enough evidence available on the possibility of producing, with these methods, cell hybrids which can maintain highly specialized biochemical processes. For Friend cells it has been shown that highly specialized biochemical processes such as stimulation of haemoglobin synthesis in the presence of dimethyl sulfoxide, can be induced in electrofused cells [IS, 191. This paper shows that electrofusion of rat adrenal and Leydig cells produced hybrids bearing the capacity to be stimulated by lutropin or adrenocorticotropin, thus synthesizing both testosterone and corticosterone.
MATERIALS AND METHODSLeydig cells were prepared by collagenase digestion of adult rat testis as described [20-211, and rat adrenocortical cells from the zona fasciculata-reticularis, were obtained by trypsin digestion [22]. The cells were resuspended in 0.3 M mannitol and electrofused by a modification of published procedures [9, 101. Fusion was performed on a perspex cylindrical chamber, having two parallel platinum electrodes (40 pm separating space). The chamber was mounted on a glass slide to allow microscope observation of pearl-chain formation and cell fusion. Two electrode wires were connected in parallel to a function generator (Health, model IG-1271), and to a home-made pulse generator. The first one was used to produce a high-frequency alternating field, resulting in cell dielectrophoresis and pearl-chain formation as described elsewhere [9, 10,12-141. The second one allowed the application of short constant voltage pulses to induce...