Altered basal firing pattern and postactivation inhibition of locus coeruleus neurons in spontaneously hypertensive rats

We compared the spontaneous unit activity and inhibition of impulse activity following antidromic activation (postactivation inhibition, PAI) of locus coeruleus (LC) neurons in spontaneously hypertensive rats (SHR) with those of LC neurons in Wistar-Kyoto rats (WKY). Spontaneous spikes of the LC were analyzed by interspike time histograms. The basal unit activity and variation coefficient of the interspike interval were decreased in SHR. The duration of the PAI which was yielded by antidromic activation from the dorsal noradrenergic bundle was shortened in SHR. These findings suggest that SHR LC neurons possess an altered basal firing pattern and inhibitory mechanism.