Adenosine receptor antagonists initiate repetitive bursting activity in the CA3 region of hippocampal slices. Although some studies have suggested that this effect is irreversible, this has been difficult to establish because many adenosine antagonists wash out of brain slices extremely slowly. Furthermore the cellular mechanism that underlies persistent bursting is unknown. To resolve these is...

The release of endogenous dopamine (DA) from rat striatal tissue was studied in an in vitro superfusion system following hormonal manipulations in vivo. Progesterone treatment in estrogen-primed ovariectomized female rats potentiated DA release stimulated either by amphetamine or potassium (K+). In addition, the amount of striatal DA released in response to K+-stimulation was influenced by the ...

Horizontal cells in the mudpuppy eyecup responded to continuous superfusion with L-glutamate, L-aspartate, kainate and quisqualate with a transient depolarization and reduction of the light evoked responses. However, in isolated retina preparations, in which these substances were applied to the photoreceptor side of the retina, the effects were sustained as long as the agonists were present. Th...

Superfusion of hippocampal slices with Mg2+ free medium (20-30 min) produced in CA1 interictal bursts and an enhancement of the Schaffer collateral synaptic response which persisted for over 2 h after return to control media. This long lasting effect, which was blocked by N-methyl-D-aspartate (NMDA) antagonists, was not associated with changes in postsynaptic cell excitability. A cut between CA...

The 86Rb efflux by high K+ was measured simultaneously during the mechanical responses in pig duodenal circular muscle using a superfusion technique. A slightly higher K+ (17.7-23.6 mM) simultaneously induced tetrodotoxin (TTX)-sensitive relaxation and 86Rb efflux. Much higher K+ (47.2-143.4 mM) contracted and also increased the 86Rb efflux markedly, but the extent of TTX-sensitive efflux remai...

Superfusion of hippocampal slices with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 2-5 microM) reversibly blocked the Schaffer collateral and mossy fibre excitatory postsynaptic potential (EPSP), while sparing the fast and slow gamma-aminobutyric acid (GABA)-mediated inhibition. Membrane potential, input resistance and spike accommodation were not altered. Inward currents induced by quisqualate...

The types and functions of histamine receptors in the submucosal arterioles of the corpus and antrum of the cat and rat stomach were studied using an in vivo microscopy technique. Change in arteriolar diameter in response to superfusion of histamine with and without antagonists was measured by an image-splitting technique. H1 and H2 histamine receptors subserving vasodilatation were demonstrate...

A period of drive in the presence of norepinephrine (NE) may be followed by the induction or acceleration of spontaneous activity. Experiments were carried out in sheep cardiac Purkinje fibers to determine whether the effects of NE on automaticity were modified during superfusion with hypoxic glucose-free Tyrode's solution and to assess the possible contribution of a-adrenergic influences on au...