Search results for "Musca"
showing 10 items of 300 documents
Control of Acetylcholine Release and of Intestinal Motility by Subtypes of Muscarine Receptors
1988
Two types of neuronal muscarine receptors have been investigated in the myenteric plexus preparation of the guinea-pig small intestine: 1. Presynaptic receptors activation of which inhibits the depolarization-evoked release of acetylcholine. Pirenzepine and dicyclomine have low affinities to the release-inhibitory receptors (pA2 values 6.9 and 7.6) which suggests that the presynaptic receptors (similar to the smooth muscle receptors) belong to the M2 subtype. The inhibition of the electrically-evoked acetylcholine release by muscarine (0.01 - 1 μmol/1) was not affected by forskolin (1μmol/l). This indicates that cyclic AMP is not crucially involved in the muscarinic inhibition of acetylchol…
The role of vagus activity in the presynaptic control of noradrenaline release from rabbit atria.
1990
Abstract On various heart preparations with the autonomic innervation left intact, vagus nerve stimulation (VNS) has been found to reduce the amount of noradrenaline (NA) that is released in response to sympathetic nerve stimulation (SNS). The following experiments were carried out on an innervated rabbit perfused atria preparation in which the overflow of NA and acetylcholine (ACh) could be determined simultaneously. VNS impulses applied at a fixed time interval before the corresponding SNS impulses reduced NA overflow when the interval was 3–10 ms (early peak) or 200–283 ms (late peak of inhibition). VNS applied 30–167 ms before SNS had no significant effect (“ineffectual period”). Both i…
Presence of muscarinic inhibitory and absence of nicotinic excitatory receptors at the terminal sympathetic nerves of chicken hearts.
1976
Nicotine (2 X 10(-4) M) or acetylcholine (5.5 X 10(-4) M) in the presence of 3 X 10(-6) M atropine did not increase the rate or amplitude of contraction in isolated atria or ventricular strips of the chicken heart; both drugs also did not cause an output of noradrenaline or adrenaline and did not evoke antidromic discharges in the right sympathetic nerves of isolated perfused chicken hearts. In contrast, "high K+-solutions" evoked an output of noradrenaline and adrenaline and caused a burst of antidromic discharges. Dimethylphenylpiperazine (DMPP; 3.1 X 10(-4) M), by a tyramine-like action, elicited a small output of noradrenaline and increased rate and amplitude of contraction" but did not…
Muscarinic mobilization of choline in rat brain in vivo as shown by the cerebral arterio-venous difference of choline.
1987
In anesthetized rats, the choline levels of cerebrospinal fluid and plasma obtained from blood collected from peripheral vessels (carotid artery, cardiac vessels) and from the transverse sinus were determined with a radioenzymatic assay. Cortical release of choline was studied using the "cup technique." The plasma choline level of the peripheral blood (11.5 mumol/L) was lower than that of the sinus blood. The resulting cerebral arterio-venous difference of choline was negative (3.2 mumol/L) and reflected the net release of choline from the whole brain. The plasma choline levels were not different irrespective of whether the rats were anesthetized with ether, urethane, or pentobarbital. Howe…
Calcium Dependence of the Mechanical Response Evoked by Okadaic Acid in Smooth Muscle
1995
The effects of okadaic acid (OA), obtained from a culture of the marine dinoflagellate Prorocentrum Lima were studied on isolated strips of rat myometrium. The contractile response evoked by OA at 5, 10, and 20 μM in normal physiological solution was unaffected in the presence of tetrodotoxin (10 μM), indomethacin (3 μM), or a cocktail of antagonists which blocked muscarinic, adrenergic, histaminergic, serotonergic, and opioid receptors. Similarly, the response to OA was unaffected in the presence of nifedipine at a concentration (1 μM) which completely or highly blocked the response to KCl (60 mM), oxytocin (1 μM), or acetylcholine (100 μM). In a Ca 2+ -free 1 mM EGTA-containing solution, …
Evidence for a respiration-modulated cholinergic action on the activity of medullary respiration-related neurons in the rabbit. An iontophoretic stud…
1989
Effects of the iontophoretically administered cholinergic agonists acetylcholine, bethanechol and DMPP on the activity of medullary respiration-related neurons were examined in urethane-anaesthetized rabbits. Inhibitory effects prevailed over excitatory effects. Analysis of cholinergic effects by cycle-triggered averaging revealed three major types of neuronal responses: (i) constant alterations of spike-density throughout the whole period of activity ("constant effects"), (ii) effects increasing during the progression of the burst of discharge or effects restricted to a particular fraction of the burst ("phasic effects") and (iii) effects which were characterized by an excitation during on…
Autonomic nervous control of the urinary bladder
2013
The autonomic nervous system plays an important role in the regulation of the urinary bladder function. Under physiological circumstances, noradrenaline, acting mainly on β(3) -adrenoceptors in the detrusor and on α(1) (A) -adrenoceptors in the bladder outflow tract, promotes urine storage, whereas neuronally released acetylcholine acting mainly on M(3) receptors promotes bladder emptying. Under pathophysiological conditions, however, this system may change in several ways. Firstly, there may be plasticity at the levels of innervation and receptor expression and function. Secondly, non-neuronal acetylcholine synthesis and release from the urothelium may occur during the storage phase, leadi…
Release of acetylcholine from murine embryonic stem cells: Effect of nicotinic and muscarinic receptors and blockade of organic cation transporter
2012
The non-neuronal cholinergic system is widely expressed in nature. The present experiments were performed to characterize the non-neuronal cholinergic system in murine embryonic stem cells (CGR8 cell line).CGR8 cells were cultured in gelatinized flasks with Glasgow's buffered minimal essential medium (Gibco, Germany). Acetylcholine was measured by HPLC combined with bioreactor and electrochemical detection.CGR8 cells contained 1.08±0.12 pmol acetylcholine/10(6) cells (n=7) which was reduced to 0.50±0.06 pmol/10(6) cells (n=6; p0.05) in the presence (4h) of 30μM bromoacetylcholine to block choline acetyltransferase. A time-dependent release of acetylcholine into the incubation medium was dem…
The non-neuronal cholinergic system in humans: expression, function and pathophysiology.
2003
Acetylcholine, a prime example of a neurotransmitter, has been detected in bacteria, algae, protozoa, and primitive plants, indicating an extremely early appearance in the evolutionary process (about 3 billion years). In humans, acetylcholine and/or the synthesizing enzyme, choline acetyltransferase (ChAT), have been found in epithelial cells (airways, alimentary tract, urogenital tract, epidermis), mesothelial (pleura, pericardium), endothelial, muscle and immune cells (mononuclear cells, granulocytes, alveolar macrophages, mast cells). The widespread expression of non-neuronal acetylcholine is accompanied by the ubiquitous presence of cholinesterase and receptors (nicotinic, muscarinic). …
New strategies for medical management of overactive bladder in children.
2011
Purpose of review The medical treatment of children with non-neurogenic overactive bladder syndrome (OAB) is still limited to a small number of drugs approved for use in childhood according to the national regulations of each country. Recent findings Over the last few years, there were several studies on the use of antimuscarinics other than oxybutynin in children, as well as some on the use of extended release oxybutynin and tolterodine and transdermal oxybutynin. It was shown that the combination of two different anticholinergics might be a well tolerated and successful option in children with OAB refractory to monotherapy, as well as administration of a receptor-selective antimuscarinic …