Simultaneous perforation of three major liver blood vessels by percutaneous transhepatic biliary drainage.
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Aged↗
Biomedical subjects
H D Allescher
Publications and source records attributed to H D Allescher.
Effect of cannabinoids on neural transmission in rat gastric fundus.
The purpose of this study was to examine the possible role of cannabinoids on the neuromuscular function of rat gastric fundus. In addition to possible direct effects on smooth muscle, the influence of cannabinoids on contractile (cholinergic) and relaxant (non-adrenergic, non-cholinergic (NANC)) neural innervation of the rat gastric fundus was investigated in vitro. Neither anandamide (an endogenous cannabinoid receptor agonist) nor Win 55,212-2 and methanandamide (synthetic cannabinoid receptor agonists) nor AM 630 (a cannabinoid receptor antagonist) showed any effect on smooth muscle activity at baseline or after precontraction with 5-hydroxytryptamine (5-HT; 10(-7) M). Electrical field stimulation (EFS) of the smooth muscle preparation (40 V; 5 Hz) caused cholinergically mediated twitch contractions that were abolished by atropine (10(-6) M) or tetrodotoxin (TTX; 10(-6) M). Anandamide and Win 55,212-2 reduced these twitch contractions in a concentration-dependent manner, an effect that could be reversed by the cannabinoid receptor antagonist AM 630 for anandamide, but not for Win 55,212-2. When NANC relaxant neural responses (presence of atropine (10(-6) M) and guanethidine (10(-6) M)) were induced by EFS, the cannabinoid receptor agonists anandamide and Win 55,212-2 reduced the relaxant response, an effect that could be reversed by the cannabinoid receptor antagonist AM 630 for anandamide, but not for Win 55,212-2. When given alone AM 630 caused an increase in the EFS-induced relaxant response. The presence of CB1 and CB2 cannabinoid receptor mRNA within the rat stomach was demonstrated by reverse transcription polymerase chain reaction (RT-PCR). The results of this study indicate that cannabinoids modulate excitatory cholinergic and inhibitory NANC neurotransmission in the rat gastric fundus. Endogenous cannabinoids may play a physiological role only in NANC inhibitory transmission, as AM 630 did not modify the electrically induced cholinergic contraction. The involved cannabinoid receptors are most likely located on neuronal structures. The present study also provides evidence that more than one receptor type is involved.
Animals↗
Characterizing voltage-dependent Ca(2+) channels coupled to VIP release and NO synthesis in enteric synaptosomes.
In enteric synaptosomes of the rat, the role of voltage-dependent Ca(2+) channels in K(+)-induced VIP release and nitric oxide (NO) synthesis was investigated. Basal VIP release was 39 +/- 4 pg/mg, and cofactor-substituted NO synthase activity was 7.0 +/- 0.8 fmol. mg(-1). min(-1). K(+) depolarization (65 mM) stimulated VIP release Ca(2+) dependently (basal, 100%; K(+), 172.2 +/- 16.2%; P < 0.05, n = 5). K(+)-stimulated VIP release was reduced by blockers of the P-type (omega-agatoxin-IVA, 3 x 10(-8) M) and N-type (omega-conotoxin-GVIA, 10(-6) M) Ca(2+) channels by ~50 and 25%, respectively, but not by blockers of the L-type (isradipine, 10(-8) M), Q-type (omega-conotoxin-MVIIC, 10(-6) M), or T-type (Ni(2+), 10(-6) M) Ca(2+) channels. In contrast, NO synthesis was suppressed by omega-agatoxin-IVA, omega-conotoxin-GVIA, and isradipine by ~79, 70, and 70%, respectively, whereas Ni(2+) and omega-conotoxin-MVIIC had no effect. These findings are suggestive of a coupling of depolarization-induced VIP release primarily to the P- and N-type Ca(2+) channels, whereas NO synthesis is presumably dependent on Ca(2+) influx not only via the P- and N- but also via the L-type Ca(2+) channel. In contrast, none of the Ca(2+) channel blockers affected VIP release evoked by exogenous NO, suggesting that NO induces VIP secretion by a different mechanism, presumably involving intracellular Ca(2+) stores.
Animals↗
Characterization of vagal input to the rat esophageal muscle.
There is recent morphological evidence for an interaction of autonomic nerve fibers and extrinsic motor nerves of the rat esophagus. The aim of the present study was to investigate a possible functional role of this autonomic innervation of vagal motor fibers on rat esophageal smooth and striated muscle function in vitro. The entire esophagus with both Nn vagi, including the Nn recurrentes, was dissected and placed in an organ bath with oxygenated Krebs-Ringer buffer. Contractile activity was measured in longitudinal direction with a force transducer. Both Nn vagi were placed on a bipolar platinum electrode 2 cm apart from the esophagus. Vagal stimulation, applied for 1 s (40 V, 0.5 ms, 20 Hz) resulted in a biphasic contractile response, which was completely blocked by tetrodotoxin (10(-6) M). The first part consisted of a tetanic striated muscle contraction, which was abolished by tubocurarin (10(-5) M) but unaffected by atropine (10(-6) M) or hexamethonium (10(-4) M). In contrast, the second part was completely abolished by hexamethonium (10(-4) M) and atropine (10(-6) M), whereas tubocurarine (10(-5) M) showed no influence, suggesting a stimulation of preganglionic nerve fibers supplying esophageal smooth muscle (muscularis mucosae). In order to characterize possible autonomic transmitters of the ENS of the esophagus, the following experiments were carried out. The magnitude of the striated muscle response was unaffected by VIP (10(-7) M), 5-HT (10(-6) M) and galanin (10(-8) - 10(-7) M), whereas they caused an inhibition of the smooth muscle response (VIP: -53.8 +/- 4.2%; galanin 10(-8) M: - 18.5 +/- 2.2%; 10(-7) M: -40.4 +/- 2.9%; 5-HT: -78.2 +/- 2.1%). The inhibitory effects of VIP and galanin on smooth muscle were reversible by the antagonists VIP 10-28 and galanin 1-15. In the presence of the nitric oxide synthase (NOS) inhibitor L-NNA (10(-4) M), the smooth and striated muscle contraction were not significantly influenced. Exogenous application of the NO-donor DEA-NO (10(-4) M) reduced the smooth muscle contraction by -81.6 +/- 7.4%, but had no significant effect on the striated muscle contraction. Though immunohistochemical findings are highly suggestive of an nitrergic autonomic modulation of striated muscle contraction by enteric neurons, we could not demonstrate a NO-mediated action on striated muscle activity. Therefore, the physiological relevance of the immunohistochemical findings remain unclear.
Animals↗
Functional coupling between nitric oxide synthesis and VIP release within enteric nerve terminals of the rat: involvement of protein kinase G and phosphodiesterase 5.
1. The subcellular mechanisms involved in the effect of nitric oxide (NO) on the release of vasoactive intestinal polypeptide (VIP) were examined in synaptosomes isolated from rat small intestine. 2. VIP release was stimulated by the NO donor SNAP (10(-7)-10(-4) M) in an oxyhaemoglobin-sensitive manner. The presence of the guanylate cyclase inhibitor ODQ (10(-5) M), or inhibition of protein kinase G (PKG) by KT 5823 (3 x 10(-6) M) or Rp-8Br-PET-cGMPS (5 x 10(-7) M), antagonized the SNAP-induced VIP release, suggesting a regulatory role of PKG, confirming previously published data from enteric ganglia. This finding was further supported by the fact that direct PKG activation by the stable cGMP analogue 8-pCPT-cGMP stimulated VIP secretion to the same extent as SNAP. 3. Basal VIP secretion was enhanced in the presence of zaprinast, an inhibitor of cGMP-dependent phosphodiesterase 5 (PDE 5), suggesting a functional role of PDE 5 in NO-cGMP signalling. Supportive evidence for this finding was obtained by demonstration of the presence of PDE 5 using RT-PCR. 4. Stimulation of endogenous NO production by L-arginine was also effective in releasing VIP. The effect was abolished in the presence of KT 5823, but was insensitive to oxyhaemoglobin (10(-3) M), suggesting that an interaction between NO and VIP is likely to occur within the same nerve terminal rather than between terminals. 5. NO synthesis was not affected by VIP (10(-8)-10(-5) M), suggesting that there is no feedback regulation between the NO and the VIP pathways. 6. These findings support the notion that an anatomical and functional interrelationship exists between NO and VIP in enteric nerve terminals and that complex signalling mechanisms involving PKG and PDE 5 contribute to NO-induced VIP release.
3',5'-Cyclic-AMP Phosphodiesterases↗
[Hemosuccus pancreaticus (bleeding into the pancreatic duct). A rare complication of pancreatitis].
HISTORY AND ADMISSION FINDINGS: A 41-year-old man was admitted because of recurrent tarry stools and dizziness. Chronic pancreatitis induced by alcoholism was known. The main abnormal laboratory finding was anaemia (haemoglobin 4.6 g/dl, erythrocytes 2.28/fl). INVESTIGATIONS, TREATMENT AND COURSE: At endoscopy of the oesophagus, stomach and duodenum, fresh blood was found in the duodenum, a small trickle of blood coming from the papilla of Vater. Endoscopic retrograde cholangiography discovered no abnormality in the biliary system. Selective contrast imaging of the pancreatic duct demonstrated a short prepapillary stenosis and a prestenotic dilatation (up to 15 mm diameter) of the pancreatic duct with a cloudy contrast filling defect. After catheter withdrawal from the pancreatic duct blood spurted from the papilla. Emergency angiography revealed pseudoaneurysmatic dilatation of the gastroduodenal artery in the region of the head of the pancreas. At selective catheterization this artery was successfully occluded with metal coils placed both proximally and distally to the source of bleeding. CONCLUSION: Gastrointestinal bleeding is a rare but potentially life-threatening complication of pancreatitis. When searching for bleeding in the upper gastrointestinal tract, the papilla of Vater should be looked for as a possible source. Bleeding from the pancreas occurs particularly in pancreatitis, pancreatic pseudocyst or pancreatic tumour.
Adult↗
[Endoscopy within the network of diagnostic imaging].
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Diagnostic Imaging↗
Pivotal role of the interstitial cells of Cajal in the nitric oxide signaling pathway of rat small intestine. Morphological evidence.
The nitric oxide (NO) signaling pathway is a major nonadrenergic-noncholinergic transmitter mechanism in the enteric nervous system. Our aim was to localize the enzymes in question, i.e., neuronal nitric oxide synthase (nNOS), soluble guanylate cyclase (sGC), and cGMP-dependent kinase type I (cGK-I) in rat small intestine by indirect immunofluorescence. nNOS staining was found in neurons of the myenteric plexus and in varicose nerve fibers mainly in the circular muscle layer. The cells positive for neurokinin-1 (NK-1) receptor and c-kit (interstitial cells of Cajal, ICC) in the deep muscular plexus (DMP) did not show nNOS reactivity, but nNOS-positive nerve fibers were directly adjacent to them. sGC was found in flattened cells surrounding myenteric ganglia (periganglionic cells, PGC), in ICC of the DMP, faintly in smooth muscle cells (SMC), and in cells perivascularly scattered throughout the circular muscle layer. cGK-I immunoreactivity was found abundantly in PGC (which presumably are ICC), in ICC of DMP, in SMC of the innermost circular and longitudinal muscle layers, but less intensively in the outer circular layer. Weak cGK-I staining occurred in nerve cells within the myenteric and submucosal plexus. Conclusively the key enzymes of the NO signaling pathway are differentially distributed: Occurrence of nNOS exclusively in neurons and the presence of sGC and cGK-I predominantly in ICC suggest a sequence of neuronal NO release, activation of ICC, and consecutive smooth muscle relaxation. ICC of the DMP seem to be the primary targets for neurally released NO.
Animals↗
A new system for rapid large-caliber percutaneous transhepatic drainage in patients with obstructive jaundice: a prospective randomized trial.
UNLABELLED: BACKGROUND AND STUDY, AIMS: Percutaneous access to the biliary tract is an important diagnostic and therapeutic tool in the management of biliary diseases. It is usually chosen when the endoscopic approach via endoscopic retrograde cholangiopancreatography (ERCP) fails, or is not possible. Once established, the percutaneous tract is then used for the treatment of biliary stones and strictures. To establish a percutaneous tract with a caliber large enough for cholangioscopy to be performed, or for a large-bore permanent drainage tube to be inserted, stepwise dilation up to 14 Fr or 16 Fr is usually required. We present here a new method of rapid dilation using specially designed materials, including a stiffenable guide wire and specially adapted bougies. PATIENTS AND METHODS: Consecutive patients undergoing percutaneous drainage for biliary diseases were included in this prospective study, over a 19-month period. After establishment of a 10-Fr transpapillary drain, the patients were randomly assigned to either conventional percutaneous transhepatic biliary drainage (PTBD) or stepwise dilation using the new method, aiming at a need for only one further session, using a specially designed stiffenable metal guide wire of 6.6 Fr and plastic bougies. The details of the procedure (duration, materials used, technical ease), initial and later complications, assessment by the patients, and procedural costs were compared between the two groups. RESULTS: Of the 60 patients included, 29 were randomly assigned to group I (the new method) and 31 to group II (the conventional approach); there were no significant differences between the two groups in terms of clinical data or biliary pathology. The clinical efficacy of PTBD was similar in the two groups, although three patients in group II were switched to the new procedure because of failure of dilation using the conventional approach. The rates of major complications (four of 29 in group I, five of 31 in group II) and patient tolerance were also similar. However, the new procedure led to a significant reduction in the cumulative procedure duration (20.1 minutes vs 30.1 minutes), mean number of sessions (1.1 vs. 1.7), and mean number of hospital days (2.0 vs 5.5), and was therefore also cost-effective, reducing costs from a mean of 5813 to 2581 German marks (DM) per patient. CONCLUSIONS: The new system for rapid establishment of large-caliber PTBD offers significant advantages in terms of saving hospital resources while maintaining clinical efficacy.
Adult↗
Treatment of achalasia: botulinum toxin injection vs. pneumatic balloon dilation. A prospective study with long-term follow-Up.
BACKGROUND AND STUDY AIMS: In patients with achalasia, intrasphincteric injection of botulinum toxin (BTX) has been suggested as an alternative regimen to balloon dilation and has been shown to be superior to placebo injection. The aim of the present study was to test the effectiveness, the long-term outcome and the cumulative costs of BTX injection in consecutive patients with symptomatic achalasia in comparison with pneumatic balloon dilation. PATIENTS AND METHODS: 37 patients, who presented with symptomatic achalasia between January 1994 and December 1996 were treated with either BTX injection (n = 23) or pneumatic dilation (n = 14). Patients with short-term or long-term symptomatic failures of the initial procedure were treated again, either with the same or with the alternative method, depending on the initial response and on the patient's wish. Symptoms were assessed using a global symptom score (0 - 10) which was evaluated before treatment and 1 week, 1 month and then every 6 months after the treatment. In addition, body weight and recurrence of symptoms were noted and manometry was carried out before and after treatment. The patients were regularly contacted for the long-term follow-up. RESULTS: There were significant improvements in the global symptom scores of all patients treated, in both the BTX injection group (before 8.2 +/- 1.3, after 3.0 +/- 1.6) and the dilation group (before 8.3 +/- 1.1, after 2.3 +/- 1.9). There was also a significant decrease of lower esophageal sphincter pressure after treatment in the BTX group and the dilation group. There were no significant differences with regard to overall treatment failure and long-term outcome between patients who had or had not received previous treatment. No major complications were encountered in either group. An actuarial analysis over 48 months comparing patients receiving BTX injection or balloon dilation demonstrated that after 12 months neither therapy was significantly superior. After 24 months a single pneumatic dilation was superior to a single BTX injection, and after 48 months all patients treated by BTX injection had experienced a symptomatic relapse. In contrast, 35 % of all patients treated by dilation and 45 % of patients treated successfully by dilation were still symptom-free in an intention-to-treat analysis after 48 months. When the overall costs of treatment and further treatment after recurrence were compared, dilation and BTX injection showed a similar cost-effectiveness (costs per symptom-free day) after 48 months. CONCLUSIONS: BTX injection, which can be performed in an outpatient setting, is as safe and cost-effective as balloon dilation in symptomatic achalasia. Taking into account the lower long-term efficacy of BTX injection therapy, however, it is an alternative only in a minority of older or high-risk patients.
Actuarial Analysis↗
Treatment of non-ulcer dyspepsia: a meta-analysis of placebo-controlled prospective studies.
BACKGROUND: Dyspeptic symptoms are commonly reported complaints in clinical practice and are mostly the result of functional disorders. Empirical treatment with histamine H2-receptor blockers or gastroprokinetics for 2-4 weeks has frequently been proposed as first line management of these patients. The clinical trials which support the use of these agents, show a high variation in clinical success rate and benefit of these treatments. METHODS: The available clinical trials were evaluated, pooled where appropriate and subjected to a meta-analysis with the principal goal to provide valid treatment recommendations for patients with non-ulcer dyspepsia. In the present meta-analysis 19 studies on gastroprokinetics (cisapride, domperidone) and 10 studies on histamine H2-receptor antagonists (cimetidine, ranitidine) were included. RESULTS: Based on these studies, a total of 1540 patients were evaluated for histamine H2-receptor antagonists (verum n = 786, placebo n = 754) and 1235 patients for gastroprokinetics (verum n = 616, placebo n = 619). The probability for treatment success compared to placebo was 0.2026 (0.1261; 0.2791) for histamine H2-receptor antagonists and 0.4029 (0.3042; 0.5069) for gastroprokinetics. CONCLUSIONS: Based on these data both treatments are significantly more effective than placebo in the symptomatic treatment of non-ulcer dyspepsia, with gastroprokinetics (cisapride, domperidone) being more effective than histamine H2-receptor antagonists (cimetidine, ranitidine).
Cimetidine↗
Autoantibody profile in progressive systemic sclerosis as markers for esophageal involvement.
We investigated the relationship between the severity and extent of esophageal involvement in patients with progressive systemic sclerosis (PSS) and the autoantibody profile. We studied 37 consecutive patients with PSS and compared their results to 25 healthy volunteers. Patients with PSS were separated into three subgroups: group 1 (antinuclear antibody [ANA] [+/-], anti-Sc170 antibody [Scl70] [-], and anticentromere antibody [ACA] [-]), group 2 (ANA [+], Scl70 [+], and ACA [-]), and group 3 (ANA [+], Scl70 [-], and ACA [+]). The lower esophageal sphincter pressure and the mean proximal esophageal amplitude were significantly lower in group 3 when compared with group 1, group 2, and the healthy controls. Distal esophageal aperistalsis was noted in 85% of group 3, 40% of group 2, and 30% of group 1. An involvement of esophageal motility was found in 100% of the patients with ACA. Our results suggest that esophageal involvement is more pronounced in patients with PSS with ACA as compared with patients with only Sc170 or ANA.
Adult↗
Pharmacoeconomic issues of the treatment of gastroesophageal reflux disease.
Gastroesophageal reflux disease (GERD) is one of the most common diagnoses in a gastroenterologist's practice. Gastroesophageal reflux (GER) describes the retrograde movement of gastric contents through the lower oesophageal sphincter (LES) to the oesophagus. GER can occur physiologically and may be accompanied by symptoms. The introduction of endoscopes and ambulatory devices for continuous monitoring of oesophageal pH (24 h pH monitoring) has led to great improvement in the ability to diagnose reflux disease and reflux-associated complications. The development of pathological reflux and GERD can be attributed to many factors. Pathophysiology of GERD includes transient lower oesophageal sphincter relaxations (TLESRs), incompetent LES because of a decreased lower oesophageal sphincter pressure (LESP) and deficient or delayed oesophageal acid clearance. Uncomplicated GERD may be treated by modification of lifestyle and eating habits in an early stage of GERD. The various agents currently used for treatment of GERD include mucoprotective substances, antacids, H2-blockers, prokinetics and proton pump inhibitors (PPIs). Although these drugs are effective, they do not necessarily influence the underlying causes of the disease by improving the oesophageal clearance, increasing the LESP or reducing the frequency of TLESRs. The following article gives an overview regarding current concepts of the pathophysiology and pharmacological treatment of GERD stressing on pharmacoeconomic issues of the treatment and discusses the advantages and disadvantages for step-up and step-down therapy.
Antacids↗
Current concepts on pathophysiology, diagnosis and treatment of diffuse oesophageal spasm.
Diffuse oesophageal spasm is a functional oesophageal motility disorder of unknown aetiology, which appears to be due to a disturbance of the normal pharmacological timing of propulsive contraction occurring in the oesophageal body after swallowing. The lack of pathophysiological understanding may be due to the fact that there is more than one pathophysiological pathway causing symptoms of diffuse oesophageal spasm. Barium studies, oesophageal scintigraphy and fiberoptic examination can be helpful in finding the correct diagnosis, but manometry is still the gold standard of diagnostic procedures. Similar to other spastic oesophageal motility disorders, pharmacological treatment of diffuse oesophageal spasm includes nitrates, calcium antagonists, anticholinergics and antidepressants with varying beneficial effects. Botulinum toxin, which provides sufficient treatment as measured by symptom score and manometric patterns in patients with achalasia, was recently evaluated for the treatment of diffuse oesophageal spasm in small patient selections with promising results.
Biofeedback, Psychology↗
Treatment of symptomatic diffuse esophageal spasm by endoscopic injections of botulinum toxin: a prospective study with long-term follow-up.
BACKGROUND: Diffuse esophageal spasm is a rare esophageal motility disorder for which there are no satisfactory pharmacologic alternatives for treatment. The aim of this study was to investigate whether botulinum toxin (BTX) injection is an effective short- and long-term treatment for patients with symptoms caused by diffuse esophageal spasm. Whether recurrence of clinical symptoms can be successfully retreated by BTX injection was also studied. METHODS: Nine symptomatic patients (6 women, 3 men; 57-86 years) with manometrically proven diffuse esophageal spasm underwent BTX injection. One hundred IU BTX were diluted in l0 mL of saline solution and injected endoscopically at multiple sites along the esophageal wall beginning in the region of the lower esophageal sphincter and moving proximally in 1- to 1.5-cm intervals, and into endoscopically visible contraction rings. Symptom scores based on an analogue scale for dysphagia, regurgitation, and noncardiac chest pain were assessed before and after therapy, 1 day thereafter, and at 1 and 6 months. RESULTS: Symptoms improved immediately in 7 (78%) patients after 1 injection session. After 4 weeks 8 (89%) patients were in remission with a decrease in total symptom score. The total symptom score decreased from a median 8.0 (interquartile range: 6.75; 9.0) before treatment to 2.0 (1.5; 3.75) after 1 day (p < 0.01) and to 2.0 (interquartile range: 0.75; 3.0) after 1 month (p < 0.01). After 6 months all 8 patients with a response at 1 month still had a symptom score of 3 or less without further treatment. Subsequently 4 patients required reinjection 8, 12, 15, or 24 months after the initial treatment with similarly good results. No serious adverse effects were observed. CONCLUSIONS: BTX injection at several levels of the tubular esophagus is an effective treatment for patients with symptoms caused by diffuse esophageal spasm. Symptom relapse can be effectively treated by repeated BTX injection.
Aged↗
Treatment of symptomatic diffuse esophageal spasm by endoscopic injection of botulinum toxin: a prospective study with long term follow-up.
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Botulinum Toxins↗
Regulation of intracellular calcium by a signalling complex of IRAG, IP3 receptor and cGMP kinase Ibeta.
Calcium release from the endoplasmic reticulum controls a number of cellular processes, including proliferation and contraction of smooth muscle and other cells. Calcium release from inositol 1,4,5-trisphosphate (IP3)-sensitive stores is negatively regulated by binding of calmodulin to the IP3 receptor (IP3R) and the NO/cGMP/cGMP kinase I (cGKI) signalling pathway. Activation of cGKI decreases IP3-stimulated elevations in intracellular calcium, induces smooth muscle relaxation and contributes to the antiproliferative and pro-apoptotic effects of NO/cGMP. Here we show that, in microsomal smooth muscle membranes, cGKIbeta phosphorylated the IP3R and cGKIbeta, and a protein of relative molecular mass 125,000 which we now identify as the IP3R-associated cGMP kinase substrate (IRAG). These proteins were co-immunoprecipitated by antibodies directed against cGKI, IP3R or IRAG. IRAG was found in many tissues including aorta, trachea and uterus, and was localized perinuclearly after heterologous expression in COS-7 cells. Bradykinin-stimulated calcium release was not affected by the expression of either IRAG or cGKIbeta, which we tested in the absence and presence of cGMP. However, calcium release was inhibited after co-expression of IRAG and cGKIbeta in the presence of cGMP. These results identify IRAG as an essential NO/cGKI-dependent regulator of IP3-induced calcium release.
Amino Acid Sequence↗
Cysteine-rich protein 2, a novel substrate for cGMP kinase I in enteric neurons and intestinal smooth muscle.
Nitric oxide/cGMP/cGMP kinase I (cGKI) signaling causes relaxation of intestinal smooth muscle. In the gastrointestinal tract substrates of cGKI have not been identified yet. In the present study a protein interacting with cGKIbeta has been isolated from a rat intestinal cDNA library using the yeast two-hybrid system. The protein was identified as cysteine-rich protein 2 (CRP2), recently cloned from rat brain (Okano, I., Yamamoto, T., Kaji, A., Kimura, T., Mizuno, K., and Nakamura, T. (1993) FEBS Lett. 333, 51-55). Recombinant CRP2 is specifically phosphorylated by cGKs but not by cAMP kinase in vitro. Co-transfection of CRP2 and cGKIbeta into COS cells confirmed the phosphorylation of CRP2 in vivo. Cyclic GMP kinase I phosphorylated CRP2 at Ser-104, because the mutation to Ala completely prevented the in vivo phosphorylation. Immunohistochemical analysis using confocal laser scan microscopy showed a co-localization of CRP2 and cGKI in the inner part of the circular muscle layer, in the muscularis mucosae, and in specific neurons of the myenteric and submucosal plexus. The co-localization together with the specific phosphorylation of CRP2 by cGKI in vitro and in vivo suggests that CRP2 is a novel substrate of cGKI in neurons and smooth muscle of the small intestine.
Amino Acid Sequence↗