Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The contractile responses of the isolated dog uterus to acetylcholine (Ach), oxytocin (Ot), histamine (Hist) and barium chloride (Ba2+) were non-competitively blocked by compound D600. This compound was significantly more potent against Ba2+-induced contractions. Increasing the calcium (Ca2+) concentration from 0.2 to 2.5 mM reverted the inhibitory effects of D600 against Ach, Ot, Hist and 1 mM Ba2+. The blockade produced by D600 against 30 mM Ba2+ was not reversed by increasing the Ca2+ concentration. In high K+-depolarizing solution, D600 produced a parallel and concentration-dependent displacement to the right to the concentration-response curves of both Ca2+ and Ba2+. The Schild plot yielded similar pA2 values for D600 against Ca2+ and Ba2+.
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PMID:Effects of compound D600 (methoxyverapamil) on drug-induced contractions of isolated dog uterine muscle. 369 46

We compared the characteristics of Ca2+ pools involved in the contractile effect of acetylcholine (Ach), histamine (Hist), oxytocin (Oxy) and barium (Ba2+) in prepuberal untreated or estrogen plus progesterone dominated uteri. After Ca2+ (0.2 mM) withdrawal different rates of decay for cited agonists were observed. If Ca2+ concentration was increased to 2.0 mM before the Ca2+ withdrawal, the t 1/2 for Ach and Hist were markedly increased. Hormonal treatment significantly increase the rate of decay for all agonists except for Ba2+ independent of the initial Ca2+ concentration, suggesting that in this condition the tightly bound Ca2+ is absent.
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PMID:Evidence for multiple sources of calcium involved on the contractile effects of agonists in the dog uterus. Influence of ovarian sexual hormones. 401 38

1. Strips of longitudinal muscle can be obtained from guinea-pig ileum either retaining or free from Auerbach's plexus.2. The denervated strip is unresponsive to electrical stimulation by brief shocks, whether given singly or in trains; it also fails to respond to nicotine or dimethylphenylpiperazinium iodide (DMPP), and eserine causes no spasm.3. Denervated strips neither contain detectable acetylcholine (< 0.4 ng/mg), nor release it spontaneously (< 5 pg/mg/min) or in response to stimulation (< 31 pg/mg/min). The acetylcholine metabolism of the innervated strip is therefore that of the adherent Auerbach's plexus. Innervated strips had a mean acetylcholine content of 28 ng/mg, a mean resting output of 94 pg/mg/min and an output in response to stimulation at 10 c/s of 700-1200 pg/mg/min.4. By comparing the responses of innervated and denervated strips it was concluded that arecoline, methylfurmethide, alpha,beta-ethylal-gamma-tri-methylammonium propanediol iodide (2268 F), muscarine, histamine, tremorine, oxytocin, and substance P, like acetylcholine, act primarily on the smooth muscle directly; and that angiotensin, barium, potassium, m-bromophenyl choline ether and 5-hydroxytryptamine have a progressively increasing proportionate effect on the nerve plexus. Nicotine and DMPP were inactive in the absence of the plexus.5. The longitudinal muscle with its accompanying plexus contains about one quarter of the acetylcholine of the whole ileum, and is responsible for about one fifth of the output to electrical stimulation.6. The volley output of acetylcholine by the innervated strip declines sharply as rate of stimulation increases. Output of acetylcholine was reduced by morphine and by cocaine, particularly when resting or when stimulated at low rates.7. Acetylcholine output by whole ileum from guinea-pig declines in the absence of glucose, but is insulin-independent. Output by strips of ileum from rats made diabetic with alloxan was similar to that from normal rats.8. The similarity in properties of acetylcholine output from innervated strips, where it must come from nervous tissue, to that from whole ileum, and the insulin-independence of output from whole ileum suggest that the whole of the acetylcholine output of intestine is nervous in origin.9. Comparison of the acetylcholine metabolism of the innervated strip with that of the superior cervical ganglion suggests that the typical features of the former (high resting output, high volley output at low rates, low minute output at high rates of stimulation, and sensitivity to morphine) may be linked with the absence of specialized neuro-effector junctions and represent a relatively primitive transmission process.
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PMID:The origin of acetylcholine released from guinea-pig intestine and longitudinal muscle strips. 429 53

At 500 micrograms-4 mg/ml piperazine and the anti-Ascaris fraction of the ethanolic extract of the bark of the erin tree (Polyadoa umbelleta) have equipotent inhibitory effects on submaximal contractions induced by equipotent doses of acetylcholine, nicotine and 5-hydroxytryptamine on the guinea-pig ileum and the rabbit duodenum. Similar inhibitory effects were noted on: acetylcholine, adrenaline, histamine, and barium chloride-induced contractions in the guinea-pig vas deferens, oxytocin and acetylcholine-induced contractions in the non-pregnant rat uterus. These actions indicate that piperazine and erin possess definite non-specific smooth muscle depressant properties. The need for the elucidation of the chemical nature of the active constituent in "erin" and for in-vivo anti-Ascaris activity studies in man is stressed.
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PMID:Effects of piperazine citrate and of the anti-Ascaris fraction of the ethanolic extract of the bark of Polyadoa umbellata (erin) on mammalian non-vascular smooth muscle. 647 82

The general pharmacology of aclacinomycin A, a new antitumor antibiotic, was studied in mice, rats, guinea-pigs, frogs, rabbits and dogs. The LD50 values of aclacinomycin A were 32.5 mg/kg (i.v.), 30.1 mg/kg (i.p.), 33.9 mg/kg (s.c.) and 69.7 mg/kg (p.o.), respectively in male mice, and 28.8 mg/kg (i.v.), 21.1 mg/kg (i.p.), 26.4 mg/kg (s.c.) and 58.6 mg/kg (p.o.), respectively in male rats. Aclacinomycin A had no effect on the central nervous system except potenciation of the pentobarbital sodium-induced anesthesia in mice. The contraction of isolated heart was stimulated in frogs while slightly inhibited in rabbits at higher concentration. Transient increases in the heart rate and the blood flow of peripheral vasculature were observed but the blood pressure was slightly lowered with respiratory excitation in anesthetized rabbits and dogs. The ECG (II-lead) demonstrated slight depression of R wave amplitude and slight sinus arrhythmia in dogs. Aclacinomycin A inhibited the contraction of isolated smooth muscle and antagonized some spasmogens. It inhibited the spontaneous movement of isolated rabbit ileum and rat uterus at higher concentration, and antagonized acetylcholine, histamine, serotonin and barium chloride in the contraction of isolated guinea-pig ileum. The antagonism was competitive to oxytocin and noncompetitive to acetylcholine in rat uterus, and noncompetitive to noradrenaline in rat deferent duct. The drug showed no apparent effect on the gastrointestinal propulsion in mice and on mucous membrane of the stomach in rats. However, it depressed gastric acid secretion in rats while slightly increased bile secretion in guinea-pigs. Urine volume and urinary excretion of electrolytes (Na+, K+) decreased in rats. Vascular permeability was slightly inhibited by the drug in rabbits and mice. No hemolytic effect was shown. Aclacinomycin A showed no antigenicity in anaphylactic reaction and SCHULTZ-DALE reaction in guinea-pigs.
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PMID:[General pharmacology of aclacinomycin A (author's transl)]. 692 61

The contraction of the potassium depolarized pulmonary artery of the guinea pig was diminished by the calcium antagonists nifedipine, gallopamil, diltiazem, verapamil and prenylamine. The drugs are listed here in order of activity. The uptake of 45Ca of the depolarized pulmonary artery was reduced by nifedipine, verapamil and prenylamine in this order of activity. The depression of the coronary flow of the isolated guinea pig heart, which was brought about by barium chloride, antigenic rabbit serum or vasopressin plus oxytocin was reduced by infusion of prenylamine. The positive inotropic effect of K-strophanthin on the isolated, electrically stimulated left atrium of the guinea pig heart was reduced by gallopamil, verapamil, prenylamine, diltiazem and nifedipine in this order of activity.
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PMID:Effects of calcium antagonists on coronary spasm and pulmonary artery contraction in comparison to their antagonistic action against K-strophanthin in isolated guinea pig atria. 710 Feb 59

The influence of androgen treatment during the neonatal period on the contractions induced in dog uteri by acetylcholine, oxytocin, histamine and barium chloride was studied in vitro. An increase in the sensitivity of preparations was observed to acetylcholine and oxytocin, represented by leftward shifts in the ED50 values of these agonists. On the other hand the ED50 values for histamine and barium chloride remained unchanged. The relative responsiveness (p) remained unaltered for all the agonists studied. These effects differ from those observed in the uterus of neonatally androgenized female rats.
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PMID:Effects of neonatal androgenization upon the pharmacological reactivity of dog uteri. 716 22

Guinea pig magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) were studied using the in vitro slice preparation. Intracellular recordings were made with biocytin-filled electrodes, permitting immunocytochemical identification of the recorded cells as arginine vasopressin- (AVP) versus oxytocin- (OT) containing. Only AVP cells displaying a depolarizing potential (DP) fired phasically. The DP was associated with a transient inward current measured in voltage clamp, which exhibited a number of properties of the T-type calcium current: activation threshold of -64 mV, time course of up to 250 ms, blockade by nickel and augmentation by barium chloride. This current has not been reported previously in SON neurons. The T-type current (IT) was always associated with a damped oscillation of the membrane following the offset from hyperpolarizing steps. In all cells tested, an apamin-sensitive afterhyperpolarization (AHP) was observed, similar to the calcium-dependent potassium current (IK, Ca) described in rat SON and other CNS regions. Therefore, as with other CNS regions displaying damped oscillations, guinea pig SON cells possess both an IT and an IK, Ca. We have previously described an Ih activating at hyperpolarized potentials in these cells, which depolarizes the membrane to a range in which the IT and IK, Ca can interactively support oscillations. In summary, the IT and associated depolarizing potential appears to be a requisite feature for phasic firing in AVP cells of guinea pig SON.
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PMID:Role of a T-type calcium current in supporting a depolarizing potential, damped oscillations, and phasic firing in vasopressinergic guinea pig supraoptic neurons. 841 16

The GABAB receptors GABAB-R1 and GABAB-R2 have been cloned in several mammalian species, and the functional receptor has been shown to exist as a heterodimeric complex. We have cloned guinea pig GABAB-R1 and GABAB-R2 receptor sequences and, using in situ hybridization and immunocytochemistry for vasopressin (AVP), we found that GABAB-R1 and -R2 receptors are expressed in vasopressin neurones of the supraoptic (SON) and paraventricular nuclei (PVN). Therefore, we used both sharp electrode and whole-cell patch recording techniques to examine the effects of the selective GABAB agonist baclofen on SON and PVN magnocellular neurones and to determine the coupling of the GABAB receptor to effector pathways. Recordings were made in coronal hypothalamic slices from both female (ovariectomized) and male guinea pigs. In the presence of tetrodotoxin (TTX), baclofen hyperpolarized (DeltaVmax = 5.6 mV, EC50 = 2.3 microM) SON magnocellular neurones (n = 27) under current clamp, or induced an outward current that reversed at EK (DeltaImax = 24.2 pA) in PVN magnocellular neurones (n = 33) under voltage clamp. Seventeen of the 24 biocytin-labelled SON magnocellular neurones were identified as AVP neurones, and ten of the 33 biocytin-labelled PVN neurones were identified as AVP or neurophysin-containing neurones, although all of the cells were clustered in the vasopressin-rich core. In the absence of TTX, baclofen activated an outward K+ current that hyperpolarized SON and PVN neurones and significantly reduced their firing rate. The outward current showed inward rectification and was blocked by the K+ channel blocker barium and the GABAB receptor antagonist CGP 35348. Therefore, GABAB receptors are coupled to inwardly rectifying K+ channels in SON and PVN magnocellular neurones and may play a prominent role in modulating phasic bursting activity in guinea pig vasopressin neurones.
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PMID:Baclofen inhibits guinea pig magnocellular neurones via activation of an inwardly rectifying K+ conductance. 1281 53

Present study was conducted on prostaglandin F2alpha (PGF2alpha), oxytocin, (OT), potassium chloride (KCI) and barium chloride (BaCl2) pre-contracted perimetrial uterine strips of dioestrus and pregnant buffaloes to evaluate the tocolytic efficacy of selective beta2 adrenoceptor agonists-albuterol (salbutamol) and terbutaline. Cumulative concentration-response curves of both the beta2 adrenoceptor agonists were constructed and the mean effective concentration (EC50) values determined and compared statistically. Based on the comparative EC50 values in relaxing the pre-contracted uterine strips with different spasmogens, the rank order potency of albuterol was found to be--PGF2alpha > BaCl2 > OT > KCl on uterine strips from dioestrus animals, while OT> BaCl2> PGF2alpha >KCl on the uterine strips of pregnant buffaloes. The rank order potency of terbutaline on uterine strips from dioestrus stage animals was- BaCl2 > OT > KCl > PGF2alpha, while BaCl2 > PGF2alpha > KCl > OT on uterine tissues of pregnant animals. Thus, irrespective of the state of uterus, whether gravid or non-gravid, KCl-depolarized uterine tissues required comparatively higher concentrations of albuterol or terbutaline to produce tocolytic effect. High concentrations of K+ in biophase may have interfered with the beta2 adrenoceptor agonists-induced outward K+ current and hyperpolarization. From the results of present study, it was evident that selective beta2 adrenergic agonists had good tocolytic efficacy on the uterus of buffaloes. Further, indirectly the possibility of existence and activation of K(Ca) channels by selective beta2 adrenoceptor agonists in mediating tocolysis of buffalo myometrium can not be ruled out, however, detailed studies using specific K(Ca) channel blockers are required for characterizing the nature of such channels in buffalo uterus.
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PMID:Evaluation of tocolytic efficacy of selective beta2 adrenoceptor agonists on buffalo uterus. 1546 86


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