Using electrical field stimulation of epithelium-denuded intact guinea pig tracheal tube preparations, we studied the presence and role of prejunctional β2-adrenoceptors by measuring evoked endogenous acetylcholine (ACh) and norepinephrine (NE) release directly. Analysis of ACh and NE was through two HPLC systems with electrochemical detection. Electrical field stimulation (150 mA, 0.8 ms, 16 H...

1. Since intermittent ischaemia may play an important role in the aetiology of Inflammatory Bowel Disease, particularly Crohn's Disease, a pharmacological model of neuronal ischaemia was applied to guinea-pig isolated intestinal preparations to mimic the acute effects of reduced blood flow on intestinal motility. 2. Neuro-effector transmission and smooth muscle performance were examined in myen...

Sympathetic nerves release norepinephrine and ATP onto mesenteric arteries. In deoxycorticosterone acetate (DOCA)-salt hypertensive rats, there is increased arterial sympathetic neurotransmission attributable, in part, to impaired prejunctional regulation of norepinephrine release. Prejunctional regulation purinergic transmission in hypertension is less well understood. We hypothesized that alp...

The present study investigated the ability of a number of presynaptic snake neurotoxins (snake beta-neurotoxins) to produce nerve-evoked train-of-four fade, tetanic fade and endplate potential run-down during the development of neuromuscular blockade in the isolated mouse phrenic-hemidiaphragm nerve-muscle preparation. All the snake beta-neurotoxins tested, with the exception of notexin, produc...

Sympathetic neurons synthesize, transport, and release tissue-type plasminogen activators (t-PAs) and urinary-type plasminogen activators (u-PAs). We reported that t-PA enhances sympathetic neurotransmission and exacerbates reperfusion arrhythmias. We have now assessed the role of u-PA and plasminogen. Neurogenic contractile responses to electrical field stimulation (EFS) were determined in vas...

In addition to their direct contractile effects, histamine (Hist), serotonin [5-hydroxytryptamine (5-HT)], and leukotriene (LT) D4, in low concentrations, dramatically augment electrical field stimulation (EFS)-induced smooth muscle contractions in equine airways. To determine the mechanism of their action, we studied, in trachealis strips, the effect of these mediators on both cholinergically ...

Two main mechanisms have been suggested for the propagation of action potentials in cardiac muscle cells: (1) the free flow of local circuit current through gap junctions and (2) the effect of electrical field. Different evidences confirm each of two mechanisms. We think that gap junctions are not continuously open in a normal heart cycle; instead, they open and close intermittently. In other w...