Summary . The effects of adrenaline on the isolated frog's heart at 27° C are not antagonized by phentolamine (1·5 × 10−6m) but are abolished at 7° C. . At 27° C isoprenaline was more potent than noradrenaline, but at 7° C noradrenaline was more potent than isoprenaline. . Phenoxybenzamine (1·5 × 10−5m) or dibenamine (1·5 × 10−5m) at 7° C abolished the work output induced by adrenaline. When the temperature was raised to 24° C., adrenaline caused an increase in work output. . It is concluded that in the isolated frog heart there are at least two pools of adrenoceptors, the availability of which can be governed by temperature.

SUMMARY1. Cholinesterase staining of rat and guinea-pig extraocular muscle shows focally and multiply innervated fibres.2. The distribution of cholinesterase activities in the populations of focal endings (from singly innervated fibres) and fine motor endings (from multiply innervated fibres) was determined by a sensitive radiochemical method.3. Focal endings had a greater cholinesterase activity than fine motor endings.4. It is suggested that this difference in enzyme activities is related to the functional difference between twitch and slow fibres in extraocular muscle.

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BIJCKLEY, G., S. CONSOLO, E. GIACOBINI and F. SJOQVIST. Cholinacetylasf in innerriated and dcncrvated sympathrtir ganglia and ganglion cells o f the cat. Acta physiol. scand. 1967. 71. 348-356. Cholinacetylase ( Ch.4c) activity Jvas determined in normal and denemated lumbosacral sympathetic ganglia of the cat. Preganglionic denervation resulted in 98 per cent derrease of the ChAc. The postsynaptic Ch.4c activity was related to the proportion of presumably cholinergic cell bodies in the denervated ganglion. Chrlc was found in about 13 per cent of the cell bodies in thr 7th lumhar ganglion before as well as after denervation. The average enzyme activity in the cell derreased by about 50 per cent after denervation. The results indicate that Ch.iic is rathrr sperifically located in cholinergic presynaptic and postsynaptic structures. 'I'hc data favour the concept that sympathetic ganglia of the cat contain at least two different crll popiilations with distinct rytochemical> histochemical and pharmarological characteristics.