PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 8018848

Acetylcholine active transport by rat brain synaptic vesicles.

J R Haigh·K Noremberg·S M Parsons
View original source ↗Export metadata ↓

Abstract

Uptake of acetylcholine was studied in a synaptic vesicle fraction isolated from rat brain. Hyposmotically treated P3 vesicles took up acetylcholine (ACh) in the presence of MgATP, and the uptake was inhibited by low temperature, ammonium ions, the protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) and bafilomycin A1, a specific inhibitor of the vacuolar H(+)-ATPase. Uptake was also inhibited by drugs that bind allosterically to the ACh transporter, namely vesamicol (IC50 value of 170 nM) and 4-aminobenzovesamicol (IC50 value of 25 nM). KM and Vmax values for ACh active transport were estimated to be 5 mM and 4 nmol min-1 mg-1 of cholinergic vesciles, respectively. Active transport of ACh by synaptic vesicles partially purified from brain is mediated by a vesamicol-sensitive transporter and is dependent on a proton gradient generated by the vesicular H(+)-ATPase.

Explore related subjects

AcetylcholineAdenosine TriphosphateAnimalsBiological Transport, ActiveBrainPiperidinesRatsSynaptic VesiclesJournal ArticleResearch Support, U.S. Gov't, P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J R Haigh, K Noremberg, S M Parsons. 1994-03-21. Acetylcholine active transport by rat brain synaptic vesicles.. https://doi.org/10.1097/00001756-199403000-00009

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Carbon monoxide-mediated activation of large-conductance calcium-activated potassium channels contributes to mesenteric vasodilatation in cirrhotic rats.

Large-conductance calcium-activated potassium channels (BK(Ca)s) are important regulators of arterial tone and represent a mediator of the endogenous vasodilator carbon monoxide (CO). Because an up-regulation of the heme oxygenase (HO)/CO system has been associated with mesenteric vasodilatation of cirrhosis, we analyzed the interactions of BK(Ca) and of HO/CO in the endothelium-dependent dilatation of mesenteric arteries in ascitic cirrhotic rats. In pressurized mesenteric arteries (diameter, 170-350 microm) of ascitic cirrhotic rats, we evaluated the effect of inhibition of BK(Ca), HO, and guanylyl-cyclase on dilatation induced by acetylcholine and by exogenous CO; and HO-1 and BK(Ca) subunit protein expression. Inhibition of HO and of BK(Ca) reduced acetylcholine-induced vasodilatation more in cirrhotic rats than in control rats, whereas inhibition of guanylyl-cyclase had a similar effect in the two groups. CO was more effective in cirrhotic rats than in control rats, and the effect was hindered by BK(Ca) inhibition. The expression of HO-1 and of BK(Ca) alpha-subunit was higher in mesenteric arteries of cirrhotic rats compared with that of control animals, whereas the expression of the BK(Ca) beta1-subunit was lower. In conclusion, an overexpression of BK(Ca) alpha-subunits, possibly due to HO up-regulation with increased CO production, participates in the endothelium-dependent alterations and mesenteric arterial vasodilatation of ascitic cirrhotic rats.

Acetylcholine↗
PubMed2007

The effect of faecal diversion on human ileum.

BACKGROUND: The use of a loop ileostomy is an effective method in protecting pelvic anastomoses. Its use has increased recently, although there is some debate as to the routine use of a stoma. Reversal of the ileostomy is associated with a significant morbidity, which may be related to impaired function of the bypassed distal limb of the ileum. AIM: To investigate the changes that might occur in the distal limb after an interval of faecal diversion. METHODS: Full-thickness intestinal circular muscle (CM) strips were prepared from excised loop ileostomies taken at the time of closure. The study sample was from the distal limb and the control from the proximal limb. Contractile activity was measured using an organ bath set up to record isometric contraction after stimulation by acetylcholine (ACh). Histological sections were assessed for an index of villous atrophy, smooth muscle area, and nerve and vessel density. Analysis was with the Wilcoxon signed ranks test for paired data and the Mann-Whitney U test for unpaired data. RESULTS: Samples were acquired prospectively from 35 consecutive patients. The median time between formation and closure of ileostomy was 34 weeks. Significant reduction was observed in the strength of CM contraction, smooth muscle area and median villous index of the distal limb compared with the proximal limb. CONCLUSION: Impaired intestinal function has been proposed as a contributory factor in the morbidity that may follow closure of loop ileostomy. Significant loss of contractility and smooth muscle strength and villous atrophy occur in the distal ileal limb after faecal diversion. Methods of preventing these changes should be considered.

Acetylcholine↗
PubMed2007

Defective insulin and acetylcholine induction of endothelial cell-nitric oxide synthase through insulin receptor substrate/Akt signaling pathway in aorta of obese rats.

The actions of acetylcholine (ACh) on endothelium mainly are mediated through muscarinic receptors, which are members of the G protein-coupled receptor family. In the present study, we show that ACh induces rapid tyrosine phosphorylation and activation of Janus kinase 2 (JAK2) in rat aorta. Upon JAK2 activation, tyrosine phosphorylation of insulin receptor substrate (IRS)-1 is detected. In addition, ACh induces JAK2/IRS-1 and IRS-1/phosphatidylinositol (PI) 3-kinase associations, downstream activation of Akt/protein kinase B, endothelial cell-nitric oxide synthase (eNOS), and extracellular signal-regulated kinase (ERK)-1/2. The pharmacological blockade of JAK2 or PI 3-kinase reduced ACh-stimulated eNOS phosphorylation, NOS activity, and aorta relaxation. These data indicate a new signal transduction pathway for IRS-1/PI 3-kinase/Akt/eNOS activation and ERK1/2 by means of JAK2 tyrosine phosphorylation stimulated by ACh in vessels. Moreover, we demonstrate that in aorta of obese rats (high-fat diet), there is an impairment in the insulin- and ACh-stimulated IRS-1/PI 3-kinase pathway, leading to reduced activation with lower protein levels of eNOS associated with a hyperactivated ERK/mitogen-activated protein kinase pathway. These results suggest that in aorta of obese rats, there not only is insulin resistance but also ACh resistance, probably mediated by a common signaling pathway that controls the activity and the protein levels of eNOS.

Acetylcholine↗