A TECHNIQUE FOR FAST APPLICATION OF HEATED SOLUTIONS OF DIFFERENT COMPOSITION TO CULTURED NEURONS

A technique is described that allows the application of fast temperatu re changes (time constant approximate to 300 ms) of solutions superfus ing cultured neurones under whole-cell mode of membrane current record ing. Its principle is id heating the common outlet of the manifold whi ch consists of 12 tubes connected to barrels containing test solutions of different composition. The outlet is made from a glass capillary ( 25 mm length, 620/350 mu m outer/inner diameter) coated on the outside wall with platinum for a length of 12 mm. The heating element, a plat inum layer, is electrically connected to the probe fixed to the microm anipulator used for positioning the manifold. The solutions, driven by gravity, are applied by opening electronic valves controlled either m anually or in programmed sequences. The DC current for heating is cont rolled either manually or by external voltage command. The advantage o f the technique is that the same temperature pattern can be applied to 12 different solutions. The technique is used for classifying Sensory neurones in culture with respect to their sensitivity to heat and alg ogens; however, it is applicable to any study of the effects of increa sed temperature on the activity of ion channels in cultured cells. (C) 1998 Elsevier Science B.V. All rights reserved.