PURPOSE: The location of acetylcholinesterase-containing nerve fibers suggests a role for acetylcholine in both contractility and secretion in the prostate gland. The colocalization of nitrergic nerves with cholinergic nerves, and the cotransmission of nitric oxide with acetylcholine in cholinergic nerves, has been demonstrated in the prostate glands of various species. Thus, we investigated the effects of acetylcholine on phenylephrine-induced contraction and the correlation between cholinergic transmission and nitric oxide synthase by using isolated prostate strips of rabbits. MATERIALS AND METHODS: Isolated prostate strips were contracted with phenylephrine and then treated with cumulative concentrations of acetylcholine. Changes in acetylcholine-induced relaxation after preincubation with NG-nitroarginine methyl ester, 7-nitroindazole, and aminoguanidine were measured. The effects of selective muscarinic receptor antagonists were also evaluated. RESULTS: In the longitudinal phenylephrine-contracted strip, the cumulative application of acetylcholine (10(-9) to 10(-4) M) elicited a concentration-dependent relaxation effect. Acetylcholine-induced relaxation was inhibited not only by nitric oxide synthase inhibitors (10 microM L-NAME or 10 microM 7-nitroindazole) but also by 10 microM atropine and some selective muscarinic receptor antagonists (10(-6) M 11-([2-[(diethylamino)methyl]-1-piperdinyl]acetyl)-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one and 10(-6) M 4-diphenylacetoxy-N-methyl-piperidine). In contrast, relaxation was significantly increased by pretreatment of the strips with 10 mM L-arginine. CONCLUSIONS: Acetylcholine relaxed phenylephrine-induced contractions of isolated rabbit prostate strips. This relaxation may be mediated via both cholinergic and constitutive nitric oxide synthase with both the M2 and M3 receptors possibly playing key roles.
Acetylcholine ; Atropine ; Contracts ; Guanidines ; Indazoles ; Nerve Fibers ; Neurons ; NG-Nitroarginine Methyl Ester ; Nitrergic Neurons ; Nitric Oxide ; Nitric Oxide Synthase ; Nitric Oxide Synthase Type I ; Phenylephrine ; Prostate ; Receptor, Muscarinic M2 ; Receptor, Muscarinic M3 ; Receptors, Muscarinic ; Relaxation

BACKGROUND: Non-depolarizing muscle relaxants have their muscle relaxing effect by competing with acetylcholine (ACh) at the nicotinic receptor level. What are the effects of such muscle relaxants on the tracheal smooth muscle? This present study was set up to address the question as to how vecuronium and pancuronium influence the tracheal smooth muscle. METHODS: Sixty male Sprague-Dawley rat tracheal smooth muscles were isolated at optimal length for isometric force. The preparations were set up in an organ bath containing Tyrode's solution. And isometric force displacement transducer and physiograph were used to record the change in force. After the equilibration period the preparations were contracted with ACh 10(-5) M and carbachol 3x10(-7)M seperately. The preparations were washed with fresh tyrode's solution and allowed to return passively to resting tone. Then the cumulartive effect of ACh (from 3 10(-7) M through 10(-5) M) and carbachol (CCh, from 10(-8) M through 3 10(-6) M) were produced before and after pretreating the preparation with vecuronium (10(-5) M and 10(-6) M) and pancuronium (10(-5) M and 10(-6) M) respectively. Also, we studied the changes of contraction produced by neostigmine before and after pretreatment with vecuronium (10(-5) M and 3 10(-5) M) and pancuronium (3 10(-6) M and 3 10(-5) M). RESULTS: Vecuronium shifted the ACh dose-response curve of the tracheal contraction to the left (p<0.0001) and pancuronium shifted the curve to the right side (p<0.0001). However vecuronium shifted the carbachol dose-response curve to the right side as did pancuronium. Also the contraction effects of neostigmine after pretreatment with muscle relaxants decreased in the group pretreated with vecuronium (p<0.05) and a higher concentration of pancuronium (p<0.01), but with a low concentration of pancuronium the effect increased (p>0.05). CONCLUSIONS: Vecuronium inhibits the ACh hydrolyzing enzyme, especially acetylcholinesterase. Therefore it potentiates ACh contraction in the tracheal smooth muscle, but not the CCh contraction, while pancuronium has a different effect in comparison with vecuronium. That is, at a low concentration it reveals an antagonistic effect on the muscarinic M2 receptor and at a higher concentration it has an antagonistic effect on the muscarinic M3 receptor in the tracheal smooth muscle.
Acetylcholine ; Acetylcholinesterase ; Animals ; Baths ; Carbachol ; Humans ; Male ; Muscle, Smooth* ; Neostigmine ; Neuromuscular Nondepolarizing Agents ; Pancuronium* ; Rats* ; Rats, Sprague-Dawley ; Receptor, Muscarinic M2 ; Receptor, Muscarinic M3 ; Receptors, Nicotinic ; Transducers ; Vecuronium Bromide*

OBJECTIVE: To observe the expression of Muscarinic receptor M1, M3, M5 subunits in rat flocculus following left unilateral labyrinthectomy (UL). METHOD: The RT-PCR was used to observe the expression of Muscarinic receptor M1, M3, M5 subunits post-unilateral labyrinthectomy and investigate its effect on vestibular compensation. RESULT: Muscarinic receptor M1, M3, M5 subunits were induced decrease in both side flocculus after unilateral labyrinthectomy. The expression was the least in the 1 d flocculus of following UL. The expression is rising from the 3-7 d flocculus of following UL. No difference was observed in the 7 d and sham operation flocculus following UL. No difference was observed in the ipsilateral and contralateral flocculus at any group. CONCLUSION Muscarinic receptor M1, M3, M5 subunits were induced decrease in the flocculus after unilateral labyrinthectomy. But the significance of the change of Muscarinic receptor M1, M3, M5 subunits in the vestibular compensation is still unknown.
Animals ; Cerebellum ; metabolism ; Functional Laterality ; Gene Expression ; Male ; Postoperative Period ; Rats ; Receptor, Muscarinic M1 ; metabolism ; Receptor, Muscarinic M3 ; metabolism ; Receptor, Muscarinic M5 ; metabolism ; Vestibule, Labyrinth ; metabolism ; surgery

The present study was aimed to investigate the positive inotropic mechanism of carbachol (CCh) on rat ventricular myocytes. The effects of CCh on L-type calcium current (I(Ca,L)) and Na(+)/Ca(2+) exchange current (I(Na/Ca)) were investigated in isolated rat ventricular myocytes. After loading myocytes with Fura-2/AM, electrically triggered Ca(2+) transient and cell shortening in single myocyte were measured simultaneously using ion imaging system with charge-coupled device (CCD) camera. CCh (100 mumol/L) increased I(Na/Ca) in forward mode from (1.18 +/- 0.57) pA/pF in the control group to (1.65 +/- 0.52) pA/pF (P<0.01) and that in reverse mode from (1.11 +/- 0.49) pA/pF in the control group to (1.53 +/- 0.52) pA/pF (P<0.01), respectively. CCh had no effect on I(Ca,L). The stimulatory effect of CCh on I(Na/Ca) was blocked by application of atropine, a non-selective M muscarinic receptor antagonist, and methoctramine, a selective M(2) muscarinic receptor antagonist. CCh (100 mumol/L) increased cell shortening from (3.00 +/- 0.67) mum in the control group to (3.55 +/- 1.21) mum. Ca(2+) transient was also increased from 203.8 +/- 50.0 in the control group to 234.8 +/- 64.3 in 100 mumol/L CCh group. KB-R7943, a selective inhibitor of reverse mode Na(+)/Ca(2+) exchange, did not change the baseline level of cell shortening and Ca(2+) transient, while completely abolished CCh-induced increments of both Ca(2+) transient and cell shortening. CCh increased cell shortening and Ca(2+) transient in the presence of nicardipine, indicating that the positive inotropic effect of CCh was through activation of Na(+)/Ca(2+) exchange. Calcium sensitivity was not changed by CCh. Both atropine and methoctramine abolished the positive inotropic effects of CCh, demonstrating that CCh induced positive inotropism via the M(2) muscarinic receptor. The results suggest that CCh increases cell contraction and Ca(2+) transient in rat ventricular myocytes. This positive inotropic effect of CCh is through activation of reverse mode Na(+)/Ca(2+) exchange, and M(2) receptors are involved in mediating CCh-induced contraction.
Animals ; Calcium ; Carbachol ; pharmacology ; Heart Ventricles ; Male ; Myocardial Contraction ; Myocytes, Cardiac ; drug effects ; Rats ; Receptor, Muscarinic M2 ; Receptors, Muscarinic ; drug effects ; Sodium ; Sodium-Calcium Exchanger ; Thiourea ; analogs & derivatives

Background: The contribution of histamine (H1) receptors inhibitory and/or β-adrenoceptors stimulatory mechanisms in the relaxant property of Ferula assa-foetida. (F. asafoetida) was examined in the present study. Methods: We evaluated the effect of three concentrations of F. asafoetida extract (2.5, 5, and 10 mg/mL), a muscarinic receptors antagonist, and saline on methacholine concentration-response curve in tracheal smooth muscles incubated with β-adrenergic and histamine (H1) (group 1), and only β-adrenergic (group 2) receptors antagonists. Results: EC50 values in the presence of atropine, extract (5 and 10 mg/mL) and maximum responses to methacholine due to the 10 mg/mL extract in both groups and 5 mg/mL extract in group 1 were higher than saline (P < 0.0001, P = 0.0477, and P = 0.0008 in group 1 and P < 0.0001, P = 0.0438, and P = 0.0107 in group 2 for atropine, 5 and 10 mg/mL extract, respectively). Values of concentration ratio minus one (CR-1), in the presence of extracts were lower than atropine in both groups (P = 0.0339 for high extract concentration in group 1 and P < 0.0001 for other extract concentrations in both groups). Conclusion: Histamine (H1) receptor blockade affects muscarinic receptors inhibitory property of F. asafoetida in tracheal smooth muscle
Receptors, Muscarinic

AIMTo optimize the method of investigating structural integration between proteins and study the integration between arrhythmia related proteins in molecular level.

METHODSImmunostaining the normal ventricular myocytes was used to observe the distribution of connexin 43 and muscarinic acetylcholine receptor (mAChR). The five mAChR subtypes were precipitated using immunoprecipitation. Then, SDS-PAGE and Western blotting with the anti-connexin 43 antibody were performed to observe whether they were structurally integrated. Further, different concentrations of detergent were used to observe whether this relationship could be broken.

RESULTSThe five subtypes of mAChR existed in the cardiac myocyte of the rat, and all the five mAChR subtypes combined with connexin 43. In the normal rat ventricular myocyte membrane, connexin 43 and M3 receptor are co-located. When adding certain concentration of detergent to the membrane protein, the integration between M3 receptor and connexin 43 was broken, and the phosphorylated form of connexin 43 integrated with M3 receptor.

CONCLUSIONThe results indicated that the structural integration between mAChR and phosphorylation of connexin 43 existed in rat ventricular myocardium, and this integration could be broken by certain concentration of detergent.

Animals ; Cell Membrane ; metabolism ; Connexin 43 ; metabolism ; Heart Ventricles ; Immunoprecipitation ; Male ; Microscopy, Confocal ; Myocytes, Cardiac ; metabolism ; Phosphorylation ; drug effects ; Rats ; Rats, Wistar ; Receptor, Muscarinic M3 ; metabolism ; Receptors, Muscarinic ; metabolism ; Sodium Dodecyl Sulfate ; pharmacology

OBJECTIVETo determine whether autoantibodies against beta(1)-adrenergic and M(2)-muscarinic receptors are related to patients with congestive heart failure (CHF).

METHODSBoth synthetic peptides corresponding to amino acids sequence 197-222 and 169-173 of the second extracellular loops of the beta(1) and M(2) receptors were used as antigens to screen sera from 265 patients.188 were congestive heart failure ( CHF) patients with different heart diseases, among them 42 were ischemic cardiomyopathy (ICD) and 52 were idiopathic dilated cardiomyopathy (IDCM) 44 were hypertensive heart disease (HHD) 50 were rheumatic valvular heart disease (RVHD); 77 were controls, among them 36 were simple hypertension and 41 were healthy donors (NC).

RESULTSPositive sera for beta(1)-adrenergic receptor was found in 45.73% (86/188) of CHF patients, while in the controls it was 10.4% (8/77) (P < 0.01); positive sera for M(2)-muscarinic receptor in CHF patients was found in 49.5% (99/188), while in the control it was 11.7% (9/77) (P < 0.01). The positive ratio of autoantibodies against beta(1)-adrenergic and M(2)-muscarinic receptors in CHF patients with cardiac function class II-III (NYHA) were significantly higher than cardiac function class IV. The average titer of autoantibodies against beta(1)-adrenergic and M(2)-muscarinic receptors of the former was significantly higher than the latter; 56.1% of patients with autoantibodies against beta(1)-adrenergic receptor had autoantibodies against M(2)-muscarinic receptor.

CONCLUSIONSAutoantibodies against beta(1)-adrenergic receptor and M(2)-muscarinic receptor were found in sera from heart failure patients with different cardiac diseases. We propose that autoantibodies against beta(1) and M(2) receptors are not only related to the IDCM, but also to cardiac structural and functional changes.

Adult ; Aged ; Amino Acid Sequence ; Autoantibodies ; blood ; Female ; Heart Failure ; immunology ; physiopathology ; Humans ; Male ; Middle Aged ; Molecular Sequence Data ; Receptor, Muscarinic M2 ; Receptors, Adrenergic, beta-1 ; immunology ; Receptors, Muscarinic ; immunology

OBJECTIVETo explore the relation between the positive rates of autoantibodies against beta(1) adrenergic receptor (beta1-receptor)and (M2-receptor) with urinary albumin excretion rate (UAER) in type 2 diabetes patients with refractory hypertension.

METHODSAutoantibodies against beta(1)- and M(2)-receptor as well as autoantibodies were determined in type 2 diabetes patients with (n = 136) or without (n = 111) refractory hypertension, hypertensive patients without renal failure (n = 60) and healthy control subjects (n = 40, control) by ELISA.

RESULTSThe positive rates of the autoantibodies against beta1-receptors (44.9%) and M(2)-receptor (37.5%) in patients with type 2 diabetes with refractory hypertension were significantly higher than those in patients with type 2 diabetes without refractory hypertension (27.9% and 24.3%, respectively, all P < 0.05), in patients with hypertension without renal failure (11.7% and 15.0%, all P < 0.01) and in healthy controls (8.3% and 7.5%, all P < 0.01). In type 2 diabetes patients with refractory hypertension and renal failure (UAER > or = 200 microg/min), the positive rates of the autoantibodies against beta(1)-receptor (87.1%, 27/31) and against M(2)-receptor (67.7%, 21/31) were significantly higher than those in type 2 diabetes patients with refractory hypertension but without renal failure (UAER 20 - 199 microg /min, 46.7%, 28/60 and 41.7%, 25/60, respectively, all P < 0.05).

CONCLUSIONThe serum beta(1)- and M (2)-receptor autoantibodies are positively associated with the UAER level and suggest that these autoantibodies against beta(1) and M(2)-receptor may play important roles in the pathogenesis of the type 2 diabetes with refractory hypertension.

Aged ; Albuminuria ; etiology ; Autoantibodies ; analysis ; Diabetes Mellitus, Type 2 ; complications ; immunology ; Female ; Humans ; Hypertension ; complications ; immunology ; Male ; Middle Aged ; Receptor, Muscarinic M2 ; immunology ; Receptors, Adrenergic, beta-1 ; immunology

OBJECTIVETo explore the role of the autoantibodies against M(2)-muscarinic receptor (M(2)-receptor), beta(1)-adrenergic receptor (beta(1)-receptor) in the development of diabetic with refractory hypertension.

METHODSSerum autoantibodies against M(2) and beta(1) were detected by ELISA using synthesized epitopes of the second extracellular loop of M(2) receptor (169 - 193) and beta(1) receptor (197 - 222) in healthy controls (n = 40), diabetic patients (n = 62), diabetic patients with non-refractory hypertension (n = 55) and diabetic patients with refractory hypertension (n = 81).

RESULTSThe positive rates of the autoantibodies against M(2) receptor and beta(1) receptor were similar among healthy controls (15.0% and 17. 5%), diabetes mellitus patients (17.7% and 14.5%) and diabetic patients with non-refractory hypertension (16.4% and 12.7%) but are significantly higher in diabetic patients with refractory hypertension (64.2% and 55.6%, P < 0.01 vs. other 3 groups).

CONCLUSIONThis finding suggests that autoimmune mechanisms might play a role in the pathogenesis of diabetic patients with refractory hypertension.

Adult ; Autoantibodies ; blood ; Diabetes Mellitus, Type 2 ; blood ; complications ; Female ; Humans ; Hypertension ; blood ; complications ; Male ; Middle Aged ; Receptor, Muscarinic M2 ; immunology ; Receptors, Adrenergic, beta-1 ; immunology

Contraction of smooth muscle is initiated by an increase in cytosolic Ca2+ leading to activation of Ca2+/calmodulin-dependnet myosin light chain (MLC) kinase and phosphorylation of MLC. The types of contraction and signaling mechanisms mediating contraction differ depending on the region. The involvement of these different mechanisms varies depending on the source of Ca2+ and the kinetic of Ca2+ mobilization. Ca2+ mobilizing agonists stimulate different phospholipases (PLC-beta, PLD and PLA2) to generate one or more Ca2+ mobilizing messengers (IP3 and AA), and diacylglycerol (DAG), an activator of protein kinase C (PKC). The relative contributions of PLC-beta, PLA2 and PLD to generate second messengers vary greatly between cells and types of contraction. In smooth muscle cell derived form the circular muscle layer of the intestine, preferential hydrolysis of PIP2 and generation of IP3 and IP3-dependent Ca2+ release initiate the contraction. In smooth muscle cells derived from longitudinal muscle layer of the intestine, preferential hydrolysis of PC by PLA2, generation of AA and AA-mediated Ca2+ influx, cADP ribose formation and Ca2+/-induced Ca2+ release initiate the contraction. Sustained contraction, however, in both cell types is mediated by Ca2+/-independent mechanism involving activation of PKC- epsilon by DAG derived form PLD. A functional linkage between G13, RhoA, ROCK, PKC- epsilon, CPI-17 and MLC phosphorylation in sustained contraction has been implicated. Contraction of normal esophageal circular muscle (ESO) in response to acetylcholine (ACh) is linked to M2 muscarinic receptors activating at least three intracellular phospholipases, i.e. phosphatidylcholine-specific phospholipase C (PC-PLC), phospholipase D (PLD) and the high molecular weight (85 kDa) cytosolic phospholipase A2 (cPLA2) to induce phosphatidylcholine (PC) metabolism, production of diacylglycerol (DAG) and arachidonic acid (AA), resulting in activation of a protein kinase C (PKC)-dependent pathway. In contrast, lower esophageal sphincter (LES) contraction induced by maximally effective doses of ACh is mediated by muscarinic M3 receptors, linked to pertussis toxin-insensitive GTP-binding proteins of the Gq/11 type. They activate phospholipase C, which hydrolyzes phosphatidylinositol bisphosphate (PIP2), producing inositol 1, 4, 5-trisphosphate (IP3) and DAG. IP3 causes release of intracellular Ca2+ and formation of a Ca2+/-calmodulin complex, resulting in activation of myosin light chain kinase and contraction through a calmodulin-dependent pathway.
Acetylcholine ; Arachidonic Acid ; Cyclic ADP-Ribose ; Cytosol ; Esophageal Sphincter, Lower ; GTP-Binding Proteins ; Hydrolysis ; Inositol ; Intestines ; Metabolism ; Molecular Weight ; Muscle, Smooth* ; Myocytes, Smooth Muscle ; Myosin Light Chains ; Myosin-Light-Chain Kinase ; Negotiating ; Phosphatidylcholines ; Phosphatidylinositols ; Phospholipase D ; Phospholipases ; Phospholipases A2 ; Phosphorylation ; Phosphotransferases ; Protein Kinase C ; Receptor, Muscarinic M3 ; Receptors, Muscarinic ; Second Messenger Systems ; Type C Phospholipases ; Whooping Cough