1. Exposure of slices of cerebral cortex from guinea pigs to electrical pulses for 10s or to noradrenaline, 5-hydroxytryptamine or histamine increases the rate of phosphorylation of unidentified proteins in the tissue; the increases in protein phosphorylation due to electrical pulses and noradrenaline were non-additive, whereas the increases due to pulses and 5-hydroxytryptamine or histamine were additive. 2. The stimulating effects of electrical pulses and noradrenaline on protein phosphorylation were antagonized by the ʲ-adrenergic blocking agents L-propranolol, dichloroisoprenaline, practolol and ICI 66082, but not by the ʱ-adrenergic blocking agents, phentolamine and phenoxybenzamine. 3. The increase in protein phosphorylation associated with electrical pulses was antagonized by 10 μm-trifluoperazine and 0.5 μm-prostaglandin E1. 4. It is postulated that under the experimental conditions used the action of electrical pulses on protein phosphorylation is mediated by noradrenaline acting through a ʲ-adrenergic receptor mechanism probably involving adenylate cyclase.
