PURPOSE To characterize the prejunctional mechanisms that control the impulse-evoked release of norepinephrine in the isolated, superfused human iris-ciliary body. METHODS Human iris-ciliary body tissue segments were preincubated with 3H-norepinephrine, superfused and electrically-stimulated in vitro to evoke the discharge of 3H-norepinephrine. The effects of prejunctional modulators on evoke...

Although the heart is considered a relatively pure source of m2 muscarinic receptors, the possible expression of other muscarinic receptor genes at discrete sites within the myocardium or by intrinsic cardiac ganglia had not been evaluated. Accordingly, the present study used in situ hybridization histochemistry with 35S-labeled oligonucleotide probes to address this issue. Initial experiments ...

Buchholz, John, and Sue P. Duckles. Chronic hypoxia alters prejunctional a2-receptor function in vascular adrenergic nerves of adult and fetal sheep. Am J Physiol Regulatory Integrative Comp Physiol 281: R926–R934, 2001.—The impact of development and chronic high-altitude hypoxia on the function of prejunctional a2-adrenoceptors was studied by measuring norepinephrine release in vitro from feta...

The aim of this study was to examine differences in prejunctional effects of different relaxants by measuring the train-of-four (TOF) fade during the onset and recovery of neuromuscular block. The relaxants studied were atracurium (225 micrograms.kg-1), mivacurium (65 micrograms.kg-1) rocuronium (300 micrograms.kg-1) and vecuronium (40 micrograms.kg-1). The TOF ratios were measured at approxima...

We performed experiments to determine whether or not acetylcholine exerts a prejunctional inhibitory effect on adrenergic neurotransmission in the human blood vessel wall. Rings of human greater saphenous veins were prepared 2 to 15 hours after death and mounted for isometric tension recording in organ chambers filled with Krebs-Ringer solution. Acetylcholine depressed contractile responses to ...

The interaction of four inhalational anesthetics (sevoflurane, isoflurane, enflurane and halothane) with pancuronium and vecuronium and also their prejunctional actions at the neuromuscular junction were quantitatively studied using rat phrenic nerve-hemidiaphragm preparations. To investigate the prejunctional effects of inhalational anesthetics, a train-of-four ratio (T4/T1) and the tetanus ra...

We have studied the relative pre- and postjunctional neuromuscular blocking effects of Org 9426 in the isolated rat hemidiaphragm muscle using twitch tension and electrophysiological recording techniques. Postjunctional effects were assessed from decreases in twitch height and from end-plate current amplitude and time constant of decay. Prejunctional effects were assessed from the fade of tetan...

experimental investigation performed in dogs in vivo has found no beneficial effect with paneuronium on pulmonary resistance, 6 contrary to what was expected by Kuwahara and Goresky from pancuronium sympathomimetic properties. Moreover, low doses of pancuronium increased pulmonary resistance (likely by blocking prejunctional M2-muscarinic receptors) whereas vecuronium was devoid of this side ef...

Although the heart is considered a relatively pure source of m2 muscarinic receptors, the possible expression of other muscarinic receptor genes at discrete sites within the myocardium or by intrinsic cardiac ganglia had not been evaluated. Accordingly, the present study used in situ hybridization histochemistry with "S-labeled oligonucleotide probes to address this issue. Initial experiments d...