The JT and QT dispersion correlate significantly with dispersion of APD90 and recovery time. The ECG assessment of dispersion of repolarization can be improved by three new ECG dispersion indexes: T peak to T end interval, total T wave area and late T wave area. These new indexes should be tested clinically.

Sustained load shortens the ERP and the mean APD90, and at the same time increases dispersion of APD90 and prolongs activation times. These findings provide additional insight into the arrhythmogenic mechanisms of sustained mechanical load.

Acetylcholinesterase is released from substantia nigra neurons, independently of cholinergic transmission. In an attempt to discover the functional significance of this phenomenon, the behavioural effects of injecting acetylcholinesterase into one substantia nigra of the rat were investigated. Following a single injection of the enzyme, intraperitoneal amphetamine evoked circling behaviour in a direction away from the side of injection. Purified acetylcholinesterase with a similar electrophoretic mobility to the endogenous secreted form, was far more potent in eliciting circling than much higher activities of commercial enzyme, consisting of several molecular species of acetylcholinesterase. Similar infusions of butyrylcholinesterase did not induce circling. Depending upon the amount of enzyme initially given, the behavioural effects of a single injection of acetylcholinesterase persisted for up to thirty days. During this period apomorphine, administered systemically, induced transient circling towards the acetylcholinesterase-treated side. It is concluded that secreted acetylcholinesterase has a functional significance within the substantia nigra, independent of cholinergic transmission. This released enzyme could exert long-term changes in the activity of the nigrostriatal system, involving modification of dopamine striatal receptors.

No abstract