scholarly journals Nitric Oxide is Involved in Metamorphic Processes in the Anuran Tadpole, Xenopus laevis

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Jennifer A. Johnson ◽  
E. Eileen Gardner ◽  
Jaishri Menon
Keyword(s):  
Nitric Oxide ◽  
Xenopus Laevis ◽  
Anuran Tadpole

scholarly journals Nitric oxide modulation of the electrically excitable skin of Xenopus laevis frog tadpoles

2007 ◽  
Vol 210 (22) ◽  
pp. 3910-3918 ◽  
Author(s):  
M. H. Alpert ◽  
H. Zhang ◽  
M. Molinari ◽  
W. J. Heitler ◽  
K. T. Sillar
Keyword(s):  
Nitric Oxide ◽  
Xenopus Laevis ◽  
Frog Tadpoles

The distribution of NADPH-diaphorase-labelled interneurons and the role of nitric oxide in the swimming system of Xenopus laevis larvae

2000 ◽  
Vol 203 (4) ◽  
pp. 705-713 ◽  
Author(s):  
D.L. McLean ◽  
K.T. Sillar
Keyword(s):  
Nitric Oxide ◽  
Xenopus Laevis ◽  
Swimming Activity ◽  
Nadph Diaphorase ◽  
Membrane Properties ◽  
Neuronal Membrane ◽  
Cycle Period ◽  
No Donor ◽  
Nos Inhibitors

The possible involvement of the free radical gas nitric oxide (NO) in the modulation of spinal rhythm-generating networks has been studied using Xenopus laevis larvae. Using NADPH-diaphorase histochemistry, three putative populations of nitric oxide synthase (NOS)-containing cells were identified in the brainstem. The position and morphology of the largest and most caudal population suggested that a proportion of these neurons is reticulospinal. The possible contribution of nitrergic neurons to the control of swimming activity was examined by manipulating exogenous and endogenous NO concentrations in vivo with an NO donor (SNAP, 100–500 micromol l(−)(1)) and NOS inhibitors (l-NAME and l-NNA, 0.5-5 mmol l(−)(1)), respectively. In the presence of SNAP, swim episode duration decreased and cycle period increased, whereas the NOS inhibitors had the opposite effects. We conclude from these data that the endogenous release of NO from brainstem neurons extrinsic to the spinal cord of Xenopus laevis larvae exerts a continuous modulatory influence on swimming activity, functioning like a ‘brake’. Although the exact level at which NO impinges upon the swimming rhythm generator has yet to be determined, the predominantly inhibitory effect of NO suggests that the underlying mechanisms of NO action could involve modulation of synaptic transmission and/or direct effects on neuronal membrane properties.

Endogenous Production of Nitric Oxide and Effects of Nitric Oxide and Superoxide on Melanotrope Functioning in the Pituitary Pars Intermedia of Xenopus laevis

Nitric Oxide ◽  
2000 ◽  
Vol 4 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Wilfried Allaerts ◽  
Werner J.H. Koopman ◽  
Bert P.J. Verlaan ◽  
Marco Buzzi ◽  
Peter A. Steerenberg
Keyword(s):  
Nitric Oxide ◽  
Xenopus Laevis ◽  
Pars Intermedia ◽  
Endogenous Production

Distribution and effects of PACAP, VIP, nitric oxide and GABA in the gut of the African clawed frog Xenopus laevis

2002 ◽  
Vol 205 (8) ◽  
pp. 1123-1134 ◽  
Author(s):  
Catharina Olsson
Keyword(s):  
Nitric Oxide ◽  
Nervous System ◽  
Gastrointestinal Tract ◽  
Xenopus Laevis ◽  
Myenteric Plexus ◽  
Nerve Cells ◽  
Nerve Fibres ◽  
African Clawed Frog ◽  
The Mean ◽  
Clawed Frog

SUMMARY The distribution and possible effects on gastrointestinal motility of pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP), nitric oxide and γ-amino-butyric acid(GABA) were investigated in the African clawed frog (Xenopus laevis)using immunohistochemistry and in vitro strip preparations. PACAP-and VIP-immunoreactive nerve fibres were common in the myenteric plexus as well as in the longitudinal and circular muscle layers all along the gastrointestinal tract. Double labelling demonstrated a close correlation between PACAP and VIP immunoreactivities, indicating that the two neurotransmitters are colocalised within the enteric nervous system. Occasionally, PACAP- and VIP-positive nerve cell bodies were seen in the myenteric or submucous plexa. In addition, VIP immunoreactivity coexisted with helospectin immunoreactivity. Nitric oxide synthase (NOS)-immunoreactive nerve cells were found in the myenteric plexus at an average density for the whole gastrointestinal tract of 4584±540 cells cm-2. The NOS-immunoreactive nerve cells were usually multipolar with an average size of 11.3±3.7 × 23.2±6.6 μm. Some NOS-immunoreactive nerve fibres were VIP-immunoreactive but not all VIP-positive fibres showed NOS immunoreactivity. GABA immunoreactivity was found in nerve fibres and nerve cells in the myenteric plexus of all regions of the gut. Few GABA-immunoreactive nerve fibres were VIP-immunoreactive. PACAP 27, VIP,sodium nitroprusside (a nitric oxide donor; NaNP) and GABA caused similar responses on spontaneously contracting circular preparations of the cardiac stomach of X. laevis. The mean force developed was decreased, mainly by a reduction in resting tension, while the amplitude of contractions was not necessarily affected. The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) increased the mean force developed, indicating a nitrergic tone in the preparations. In contrast, PACAP 27, VIP, NaNP, GABA and L-NAME had no significant effect on longitudinal strip preparations from the duodenum. These results indicate that PACAP, VIP, nitric oxide and GABA, which are known to be important inhibitory neurotransmitters in other vertebrates, are widely spread in the enteric nervous system of Xenopus laevis and may be involved in the inhibitory control of gastric motility. Although no effect of PACAP,VIP, nitric oxide or GABA on the longitudinal strips of the duodenum was seen in this study, this does not rule out the possibility that they might play an important role in controlling intestinal motility as well.

scholarly journals Nitric oxide synthase and background adaptation in Xenopus laevis

1997 ◽  
Vol 14 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Wilfried Allaerts ◽  
Ruud Ubink ◽  
Jan de Vente ◽  
Rienk Tuinhof ◽  
Bruce G Jenks ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Xenopus Laevis ◽  
Background Adaptation ◽  
Oxide Synthase

Inhibition of Nitric Oxide Synthase Decreases Anesthetic Requirements of Intravenous Anesthetics in Xenopus laevis 

1997 ◽  
Vol 87 (6) ◽  
pp. 1479-1485 ◽  
Author(s):  
Peter H. Tonner ◽  
Jeans Scholz ◽  
Lars Lamberz ◽  
Nikolas Schlamp ◽  
Jochen Schulte am Esch
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Xenopus Laevis ◽  
Dependent Manner ◽  
Response Curves ◽  
Concentration Dependent Manner ◽  
Intravenous Anesthetics ◽  
Anesthetic Agents ◽  
Loss Of Righting Reflex ◽  
Oxide Synthase

Background Acute inhibition of nitric oxide synthase (NOS) has been demonstrated to reduce the anesthetic requirements of volatile anesthetics. Recent data suggest that not only volatile but also intravenous anesthetic agents interact with nitric oxide (NO) metabolism. The aim of this study was to examine the effect of NOS inhibition by nitroG-L-arginine-methyl-ester (L-NAME) on the anesthetic action of the intravenous anesthetics thiopental, propofol, and ketamine. Methods The anesthetic potencies of thiopental, propofol, and ketamine were determined in Xenopus laevis tadpoles in the absence and presence of L-NAME. Anesthesia was defined as loss of righting reflex for 5 s. A nonlinear logistic regression curve was fitted to the data and half-maximal effective concentrations (EC50) were calculated. A second set of experiments was performed with different concentrations of L-NAME in the presence of the previously determined the EC50 of the intravenous anesthetics. Results The EC50s of the anesthetics thiopental, propofol, and ketamine were determined to be 25.5 +/- 2.0 microM, 1.9 +/- 0.1 microM, and 59.7 +/- 0.7 microM, respectively. The addition of L-NAME shifted the concentration-response curves to the left in a concentration-dependent manner. In the presence of 1 mM L-NAME, the EC50 of thiopental was reduced by 43%, the EC50 of propofol by 26%, and the EC50 of ketamine by 63%. The addition of D-NAME did not change the EC50 values of the three anesthetics. In the presence of L-arginine, the effect of L-NAME on the EC50 of thiopental was reversed. When administered by itself in a concentration range from 0.1 microM to 10 mM, L-NAME did not alter the behavior of the tadpoles. Conclusions The results of the present study show that acute inhibition of NOS by L-NAME results in reduced anesthetic requirements of the intravenous anesthetics thiopental, propofol, and ketamine. This interaction of acutely administered L-NAME and intravenous anesthetics indicates that the NO-cyclic guanosine 3',5'-monophosphate system is involved in mediating the anesthetic effect of these compounds.

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