Dapiprazole produces miosis by blocking the alpha 1 receptors in the dilator muscle of the iris.Intraocular dapiprazole for reversing mydriasis has been compared with intraocular carbachol.Ten adult rabbits of same breed, weight, and age group were used.Both pupils were dilated with one drop each of 2.5% phenylephrine and 0.5% tropicamide.After 10 minutes, when full mydriasis was present, 0.2 ml of aqueous humor was removed from the anterior chamber of each eye through a limbal puncture and replaced with equal amount of 0.5% dapiprazole solution on one eye, and with 0.01% carbachol on the other eye.Pupillary diameter recordings were performed immediately before and a few minutes after drug injection, as well as 24 hours after limbal puncture.Intraocular pressure, corneal thickness, corneal endothelial cell count, and protein in the aqueous humor were evaluated prior to surgery and one day postoperatively.The results showed no difference in the miotic efficacy of dapiprazole and carbachol.The level of aqueous humor protein was significantly higher in the carbachol-treated eyes than in the dapiprazole-treated eyes.No significant difference in intraocular pressure, corneal thickness, and corneal endothelial cell density was noted.Intraocular 0.5% daapiprazole is comparable to 0.1% carbachol in efficacy and safety with less effect on the blood-aqueous barrier.
Animal ; CARBACHOL ; CATARACT ; DAPIPRAZOLE

The classic type of transient receptor potential channel (TRPC) is a molecular candidate for Ca2+-permeable cation channel in mammalian cells. TRPC5 is rapidly desensitized after activation by G protein-coupled receptor. Herein we report the effect of dimethyl sulfoxide (DMSO) on the desensitization of TRPC5. TRPC5 was initially activated by muscarinic stimulation with 50microM carbachol (CCh) and then decayed rapidly even in the presence of CCh (desensitization). DMSO in the pipette solution slowed the rate of this desensitization. Under the control conditions, TRPC5 current spontaneously declined to 6+/-1% of the initial peak amplitude 60 sec after CCh application and to 1+/-0.5% after 120 sec. But, in the presence of 0.01%, 0.1% and 1% DMSO, TRPC5 current spontaneously declined to 55+/-2%, 68+/-1% and 100+/-0.2% of the initial peak amplitude 60 sec after CCh application and to 38+/-2%, 61+/-1% and 100+/-1% after 120 sec, respectively. The results suggest that DMSO can internally attenuate the desensitization of TRPC5 current through unknown mechanisms that remain to be elucidated.
Carbachol ; Dimethyl Sulfoxide*

Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (–)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4-GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels.
Calcium* ; Carbachol ; Fluorescence ; Permeability* ; Receptors, Muscarinic

BACKGROUND: Propofol inhibits postoperative bronchospasm. Ketamine prevents bronchospasm in asthmatic patients. The present study was designed to evaluate the effects and mechanisms of propofol and ketamine on tracheal smooth muscles. METHODS: After isolating guinea-pig tracheal preparations, the maximal tracheal tones were induced by smooth muscle constrictors(2 10 7 M carbachol, 10 5 M histamine, 30 mM K+ Krebs solution, 124 mM K+ Krebs solution). When tracheal tones stabilized, propofol or ketamine was added cumulatively to obtain the concentration-relaxation curves, and calculated the ED50 and ED95. RESULTS: Propofol and ketamine decreased maximal tracheal tones in the concentration-dependent manners. The ED50 and ED95 of propofol were lowest in the histamine group, highest in the 30 mM K+ Krebs solution group. The ED50 and ED95 of ketamine were lowest in the 124 mM K+ Krebs solution group, highest in the histamine group. CONCLUSIONS: The relaxant effects of propofol and ketamine involve with all receptors in nonspecific way. However, propofol may inhibit more strongly the histamine mediated mechanism of tracheal contraction and ketamine may involve more strongly with Ca++ channel.
Bronchial Spasm ; Carbachol ; Histamine ; Humans ; Ketamine* ; Muscle, Smooth* ; Propofol*

BACKGROUND: The stomach can be generally classified anatomically into three parts; fundus, corpus, and antrum. It has not been well demonstrated how the three regions contribute to specified gastric motility. In the present study, the regional differences on contractile response and intracellular Ca2+ levels ([Ca2+]i) were investigated in a mouse gastric muscle. METHODS: An isometrical contraction was measured with a computerized physiograph, and [Ca2+]i was measured with fura-PE3/AM, a fluorescent Ca2+ indicator in gastric smooth muscle from mice. RESULTS: Carbachol (CCh), a potent muscarinic receptor agonist, generated rhythmic contractions in a dose dependent manner, superimposed on tonic components in the antral muscle. Whereas similar contractile responses to CCh was obtained in the antrum, CCh evoked tonic components predominantly. CCh increased [Ca2+]i in a dose dependent manner in both the antral and fundic smooth muscle. However, the increment of [Ca2+]i in the fundus was greater than that of the antrum. Verapamil (10nM), a l-type Ca2+ channel blocker, inhibited completely the contraction and [Ca2+]i induced by CCh in the antral strips, whereas the responses in the fundus showed a resistance to verapamil. CONCLUSIONS: These results suggest that muscarinic stimulation has a regional difference on muscle contractility and [Ca2+]i, which is mediated by differences of Ca2+ movement in mouse gastric muscle.
Animals ; Carbachol ; Mice ; Muscle, Smooth* ; Receptors, Muscarinic ; Stomach ; Verapamil

BACKGROUND: Purinergic and cholinergic agonists elicit negative-inotropic and chronotropic effects, anticip-ating their protective action from the damage of overloaded myocardium. However, the actions of the agents during the ischemic insults are not yet clearly informed. The aim of this study was to investigate the role of the purinergic and cholinergic agonists on the simulated ischemic myocardium of the rat atrial fiber preparations. METHOD: Various action potential parameters (maximum diastolic potential MDP;action potential amplitude APA;velocity of phase 0 depolarization dV/dtmax;action potential duration APD90) were measured and compared in electrically paced, normal (NPSS) and modified physiological salt solution (MPSS) superfused rat atrial fibers in vitro, using conventional 3M-KCl microelectrode technique. Ischemia-simulated modified physiologic solutions were prepared by changing the solution's composition. RESULTS: Hypoxic-and/or hyperkalemic-MPSS decreased all the action potential (AP) variables. However, no significant changes of the AP variables were developed by the acidic-or glucose-free MPSS. Adenosine (Ado) and cyclopentyladenosine (CPA) only decreased the APD90 in a dose-dependent manner. Acetylcholine (Ach) and carbachol (Cch) hyperpolarized the MDP, increased the dV/dtmax with certain doses, and decreased the APD90 dose-depen-dently. The potency for APD90-decrease was greater in order, CPA>Cch>Ach>Ado. Ado and CPA did not affect the hypoxic, hypokalemic MPSS-induced dV/dtmax-decrease. On the other hand, Ach and Cch sig-nificantly inhibited the dV/dtmax-decrease by the hypoxic hypokalemic-MPSS. Ado, CPA, Ach and Cch sig-nificantly augmented the hypoxic, hypokalemic MPSS-induced APD90-decrease. The inhibition by the Ach and Cch on the MPSS-induced dV/dtmax-decrease was not affected by DPCPX, but atropine significantly attenuated the inhibition by the cholinergic agonists. DPCPX inhibited the augmentation by the Ado and CPA on the MPSS induced APD90-decrease, and atropine inhibited the effect of the cholinergic agonists. CONCLUSION: Both purinergic and cholinergic agonists not only shorten the AP duration by themselves but also enhance the AP-shortening effect elicited by the ischemia, and therefore, it is inferred that both agonists prevent further tissue damage from the ischemic insults.
Acetylcholine ; Action Potentials ; Adenosine ; Animals ; Atropine ; Carbachol ; Cholinergic Agonists* ; Hand ; Ischemia ; Microelectrodes ; Myocardium* ; Rats*

BACKGROUND: Midazolam relaxes airway smooth muscle. The aim of this study is to evaluate the influence of flumazenil or verapamil on the relaxation effects of midazolam in tracheal smooth muscle of guinea pig. METHODS: After isolating guinea-pig tracheal preparations, the maximal tracheal tones were induced by 2 10(-7) M carbachol. When tracheal tones stabilized, midazolam was added cumulatively (10(-6), 3 10(-6), 10(-5), 3 10(-5), 10(-4) M, n=14) with or without flumazenil (10(-6) M, n=15) and verapamil (10(-5) M, n=13) to obtain the concentration-relaxation curves, and then the ED50 and ED95 calculated. RESULTS: Midazolam decreased maximal tracheal smooth muscle tones in concentration-dependent manners. Pretreatment with flumazenil had no effect on the midazolam-induced relaxation. Verapamil enhanced the relaxation effect of midazolam. CONCLUSIONS: Midazolam relaxes airway smooth muscle and has synergistic effect with calcium channel blocker, verapamil.
Animals ; Calcium Channels ; Carbachol ; Flumazenil* ; Guinea Pigs ; Midazolam* ; Muscle, Smooth* ; Relaxation* ; Verapamil*

BACKGROUND/AIMS: Trinitrobenzene sulphonic acid (TNBS)-induced colonic inflammation in rat alters colonic motor function. The aims of this study were to investigate the effect of TNBS-induced colitis on the colonic motor function of a guinea pig along the course of colitis and to document persistently altered colonic motor function after resolution of inflammation. METHODS: Colitis was induced in about 300 g male guinea pigs (Hartley) by intrarectal administration of 0.3 mL TNBS in 50% ethanol, while controls received 0.3 mL of 50% ethanol or not. After 24 hours, 48 hours, 72 hours, 1 week, and 2 weeks, the distal colon was taken for the investigation of gross and microscopic findings, muscle tension, and colonic transit. RESULTS: Maximal mucosal injury and inflammation were evident from the 2nd day following the induction of colitis. Seven days after the induction of colitis, some portions of the damaged mucosa began to recover. Development of tension in response to carbachol was not altered significantly along the course of colitis. Colonic transit was delayed significantly at 3, 7, and 14 days after administration of TNBS. CONCLUSIONS: Colonic transit in TNBS-induced colitis of guinea pigs is delayed, but not linearly related to the degree of inflammation. Delayed colonic transit is not related to the muscarinic receptor-mediated contractions of circular muscle from the inflamed colon. Further studies are required to determine the mechanism(s) involved in this motor change.
Animals ; Carbachol ; Colitis* ; Colon* ; Ethanol ; Guinea Pigs* ; Guinea* ; Humans ; Inflammation ; Male ; Mucous Membrane ; Muscle Tonus ; Rats

Bowel segments are used either in a tubular or detubular configuration in bladder augmentation and substitutions. The majority of urologists agree that detubularized segments give better clinical results,but detailed studies were not investigated in animals. The present study compared the contractile response of autonomic agonists including carbachol, isoproterenol,alpha, beta-methylene ATP on detubularized and tubularized cystoplastic ileal segments. In addition, histological examinations of cystoplastic ileal segments were performed. Five rats underwent Sham operation as control and eight rats underwent detubularized ileocystoplasty and seven rats underwent tubularized ileocystoplasty. Analysis was done six weeks after surgery. The contractile responses of detubularized cystoplasty ileum to carbachol, alpha, beta-methylene ATP were significantly increased when compared to the responses of tubularized ileum and control ileum. The relaxation responses of detubularized cystoplasty ileum to isoproterenol were significantly higher than control ileum. However, in tubularized ileum, the responses to carbachol, alpha, beta-methylene ATP, isoproterenol were similar for control ileum. The responses of detubularized cystoplasty ileum to carbachol, alpha, beta -methylene ATP were significantly different from control bladder, but detubularized cystoplasty ileum showed responses that resemble control bladder more closely when compared to the responses of tubularized ileum.The histological examination showed urothelialization of cystoplastic ileum with transitional epithelium extending over and covering the junction margin of the cystoplastic ileum. These results suggest detubularized ileocystoplasty induced closer pharmacological changes in the ileal segment towards the bladder than tubularized ileocystoplasty and so we can expect detubularized ileocystoplasty gives better clinical outcome.
Adenosine Triphosphate ; Animals ; Carbachol ; Epithelium ; Ileum* ; Isoproterenol ; Rats* ; Relaxation ; Urinary Bladder

BACKGROUND: Several reports have indicated that heparin has a bronchodilative effect in asthma patients, and that it enhances airway smooth muscle contraction in vitro, protamine is known to inhibit or enhance contraction of tracheal smooth muscle. Thus the effects of protamine and heparin on airway smooth muscle contraction are not consistent. However, no report is available on the effects of enflurane on heparin and protamine tracheal smooth muscle contraction. We performed this study to evaluate the effects of heparin or protamine on the carbachol induced contraction of tracheal smooth muscle in the guinea pig. And we also evaluated the effects of enflurane on heparin or protamine induced tracheal smooth muscle contraction. METHODS: Isolated tracheal rings of the guinea pig were suspended in Krebs solution. Contractions were recorded isometrically using a transducer. Contraction was induced by carbachol (10-6 M) and then cumulative dose responses of heparin or protamine (0.006 mg/ml, 0.02 mg/ml, 0.06 mg/ml, 0.2 mg/ml, 0.4 mg/ml) and in heparin (E) group and protmine (E) group, enflurane (4.34%) was administered for 15 minute after carbachol adminstration. RESULTS: Contraction by carbachol was inhibited by level of heparin or protamine at concentrations of 0.2 mg/ml and 0.4 mg/ml. At an enflurane (4.34%) contraction was inhibited, and no further inhibition of contraction by heparin or protamine was observed. CONCLUSIONS: Heparin or protamine inhibited the tracheal smooth muscle contraction induced by carbachol at 0.2 mg/ml and 0.4 mg/ml, and no further significant inhibition of contraction by heparin or protamine was observed after enflurane administration (4.34%).
Animals ; Asthma ; Carbachol* ; Enflurane ; Guinea Pigs* ; Guinea* ; Heparin* ; Humans ; Muscle, Smooth* ; Transducers