This study was designed to investigate the effect of substitution of strontium for calcium on mechanical activity in isolated perfused spontaneously beating rat hearts. The mechanical activity of the hearts of Langendorff's preparation in conditions of low calcium and strontium-substitution for calcium was compared. The effect of norepinephrine and verapamil were also observed in those conditions. The results were as follows: 1. In low calcium, the mechanical activity of the heart preparation was significantly reduced, but when the equimolar strontium was substituted for the reduced calcium, the activity was kept at similar level to the normal condition. 2. When equimolar strontium was substituted for the total calcium in perfusate, the heart preparation stopped its beating, and it was not restored in spite of reperfusion with normal calcium perfusate. 3. Norepinephrine-induced positive inotropic effect was inhibited in low-calcium condition especially with low concentration of norepinephrine, but not in strontium-substitution for calcium. 4. Verapamil reduced the activity of the heart both in low-calcium and strontium-substitution as well as in normal calcium conditions. From above results, it was concluded that strontium served as a substitute of calcium in maintaining mechanical activity and in responsiveness to norepinephrine, and the influx of strontium through cell membrane is inhibited by verapamil as the influx of calcium.
Animals ; Calcium ; Cell Membrane ; Heart* ; Norepinephrine* ; Rats* ; Reperfusion ; Strontium* ; Verapamil

BACKGROUND: Endocrine pancreas tumor is a rare disease which incidence is less than 2% of all pancreatic tumors. But it comprises various types of tumor and usually secretes several hormones from one type of tumor although the patient with this tumor complains of sole symptom associated with only one hormone. The mechanism and clinical significance of multiple hormone secretion in the endocrine pancreas tumom are not yet clearly defined. METHODS: We analyzed retrospectively the clinicopathologic features of 20 cases which were operated at Seoul National University Hospital during the period between February 1989 and May 1998. RESULTS: The most common tumor was insulinoma (13 cases) and the second most common tumor was nonfunctioning tumor (6 cases). There was one case of somatostatinoma. Most of the patients with insulinoma complained of neuroglycopenic symptoms. There were 9 cases (45.0%) in which the tumors secreted more than two kinds of hormones, 7 cases in insulinoma, 2 cases in nonfunctioning tumors. Whether the tumor secreted multiple hormones was detected by the method of immunohistochemical staining. Though the tumors secreted more than two kinds of hormones, the patients with the tumors complained of symptoms which were associated with the cell type most strongly stained by immunohistochemical method. Whether or not the tumors secreted multiple hormones was not associated with the pathologic features such as tumor size, histologic patterns of the tumor, status of tumor cell differentiation and malignancy. CONCLUSION: From this results, we suggest that endocrine tumors of the pancreas secreted multiple hormones not by the mechanism of dedifferentiation from already differentiated endocrine cells but by the mechanism of neogenesis of multipotent islet stem cells. Since the relationship between the function of multiple hormone secretion in the endocrine pancreas tumors and islet stem cell would be significant, further study should be needed to find out the function of stem cells and application of stem cells to clinical use.
Cell Differentiation ; Endocrine Cells ; Humans ; Incidence ; Insulinoma ; Islets of Langerhans ; Pancreas* ; Rare Diseases ; Retrospective Studies ; Seoul ; Somatostatinoma ; Stem Cells

No abstract available.
Child* ; Edema* ; Gallbladder* ; Humans

This study was aimed at investigation of the stimulatory innervations on the rat urinary bladder. Detrusor muscle strips of 15 mm long were suspended in isolated muscle chambers containing 1 ml of PSS maintained at 37℃ and aerated with 95% O²/5% Co². Isometric myography was performed, and the results were as followings: Muscle strips showed “on-contraction” by electric field stimulation (EFS) frequency-dependently. The EFS-induced contraction was not affected by hexamethonium, a ganglion blocker, but abolished by tetrodotoxin, a nerve conduction blocker. Physostigmine, a cholinesterase inhibitor enhanced the EFS-induced contraction which was inhibited by hemicholinium, an inhibitor of choline uptake at the cholinergic nerve ending. Such an EFS-induced contraction was antagonized by atropine only partially, and the atropine-resistant portion was completely abolished by the desensitization of purinergic receptors by prolonged incubating of the strips in the presence of high concentration of ATP. Bethanechol, a cholinergic agonist, elicited concentration-dependent contraction. Adenosine triphosphate (ATP), a purinergic agonist, induced a weak but concentration-dependent contraction of short duration. Bethanechol-induced contraction was not affected by ATP-desensitization, and ATP-induced contraction was not affected by tetrodotoxin. These results suggest that there are at least two main stimulatory components of innervations in the detrusor muscle, cholinergic muscarinic and purinergic; and those receptors are independent each other.
Adenosine Triphosphate ; Animals ; Atropine ; Bethanechol ; Choline ; Cholinergic Agonists ; Cholinesterases ; Ganglion Cysts ; Hemicholinium 3 ; Hexamethonium ; Myography ; Nerve Endings ; Neural Conduction ; Physostigmine ; Rats* ; Receptors, Purinergic ; Tetrodotoxin ; Urinary Bladder*

This study was designed to investigate the effect of GABA and related substances on the spontaneous contraction of rat small intestine. The rats (Sprague-Dawley), weighing 200-250g, were sacrificed by cervical dislocation, and the small intestine was isolated. Longitudinal muscle strips from duodenum, jejunum and ileum were suspended in Biancani's isolated muscle chambers and myographied isometrically. GABA and muscimol, a GABA A receptor agonist relaxed the duodenum and jejunum significantly, but baclofen-induced relaxation in those muscle strips negligible. The effectiveness of GABA and muscimol in various regions were the greatest on duodenum, and greater on jejunum than on ileum The effect of GABA and muscimol was antagonized by bicuculline, a competitive GABA A receptor antagonist and picrotoxin, a noncompetitive GABA A receptor antagonist. Duodenal relaxation induced by GABA and muscimol was unaffected by hexamethonium, but was prevented by tetrodotoxin. These results suggest that GABA inhibit the contractility of smooth muscle with distinct regional difference of efficacy, and the site of inhibitory action is the GABA A receptor existing at the presynaptic membrane of postganglionic excitatory nerves.
Animals ; Bicuculline ; Dislocations ; Duodenum ; GABA-A Receptor Agonists ; GABA-A Receptor Antagonists ; gamma-Aminobutyric Acid* ; Hexamethonium ; Ileum ; Intestine, Small* ; Jejunum ; Membranes ; Muscimol ; Muscle, Smooth ; Picrotoxin ; Rats* ; Receptors, GABA-A ; Relaxation ; Tetrodotoxin

To investigate the effect of diazepam on the contractility of the intestinal smooth muscle, longitudinal muscle strip isolated from rat ileum was prepared for myography in isolated organ bath. 1) Basal tone of ileal muscle was reduced by diazepam concentration-dependently. 2) Higher concentrations (30 and 100 microM) of diazepam inhibited (p<0.05, p<0.001) The carbachol-induced contraction in a concentration-dependent manner; but lower concentration of diazepam (10 microM) enhanced (p<0.05). 3) Histamine-induced contraction was inhibited by pretreatment with diazepam in a concentration-dependent manner. 4) Ca⁺⁺-induced tension recovery in calcium-free solution was inhibited in the presence of diazepam concentration-dependently. These results suggest diazepam reduces the contractility of the longitudinal muscle isolated from rat ileum via interference with influx of calcium into the muscle cells.
Animals ; Baths ; Calcium ; Carbachol* ; Diazepam* ; Ileum* ; Muscle Cells ; Muscle, Smooth ; Myography ; Rats*

GABA is an inhibitory neurotransmitter in central nervous system and produce sedative, antianxiety and muscle relaxing effects via GABA(A) receptor or GABA(B) receptor. Recently it is known that GABA is widely distributed throughout peripheral organs and may play a physiological role in certain organ. The vas deferens is innervated by species-difference. These study, therefore, was performed to investigate the mode and the mechanism of action of GABA on the norepinephrine-, ATP- and electric stimulation-induced contraction of vas deferens of rat. Sprague-Dawley rats were sacrificed by cervical dislocation. The smooth muscle strips were isolated from the prostatic portion and were mounted in the isolated muscle bath. PSS in the bath was aerated with 95/5%-O₂/CO₂ at 33℃. Muscle tensions were measured by isometric tension transducer and were recorded by biological recording system. 1. GABA, muscimol, a GABA(A) agonist, and baclofen, a GABA(B) agonist inhibited the electric field stimulation (EFS, 0.2Hz, 1mSec, 80V, monophasic square wave)-induced contraction with a rank order of potency of GABA greater than baclofen greater than muscimol. 2. The inhibitory effect of GABA was antagonized by delta aminovaleric acid (DAVA), a GABA(B) antagonist, but not by bicuculline, a GABA(A) intagonist. 3. The inhibitory effect of baclofen was antagonized by DAVA, but the effect of muscimol was not antagonized by bicuculline. 4. Exogenous norepinephrine (NE) and ATP contracted muscle strip concentration dependently, but the effect of acetylcholine was negligible and GABA did not affect the NE-and ATP-induced contractions. 5. GABA, baclofen and muscimol did not affect basal tone, and GABA did not affect the NE-and ATP-induced contractions. 6. EFS-induced contraction was inclucling 2 distinctable components. The first phasic component was inhibited by beta gamma-methylene ATP (mATP), a desensitizing agent of APT receptor and the second tonic component was reduced by pretreatment of reserpine (3 mg/Kg, IP). 7. GABA inhibited the EFS-induced contraction of reserpinized strips, but not the mATP-treated strips. These results suggest that in the prostatic portion of the rat vas deferens, adrenergic and purinergic neurotransmissions are exist, and GABA inhibits the release of ATP via presynaptic GABA(B) receptor on the excitatory neurons.
Acetylcholine ; Adenosine Triphosphate ; Animals ; Baclofen ; Baths ; Bicuculline ; Central Nervous System ; Dislocations ; gamma-Aminobutyric Acid ; Muscimol ; Muscle, Smooth ; Neurons ; Neurotransmitter Agents ; Norepinephrine ; Rats* ; Rats, Sprague-Dawley ; Receptors, GABA-A ; Reserpine ; Transducers ; Vas Deferens*

This study was performed to investigate the effect of octreotide on the contractility of rat vas deferens. The -smooth muscle strips isolated from the prostatic portion were myographied in isolated organ bath. Electric -field stimulation (monophasic square wave, duration : 1. mSec, voltage : 50 V, frequency : 5 Hz or 30 Hz, train : 10 Sec) produced reproducible contraction. The contraction was composed of two component, first phasic component (FPC) and second tonicc component (STC).. These contractions were abolished by -tetrodotoxin (1 microM). Octreotide inhibited the field stimulation induced contractions both FPC and STC concentration- dependently. The FPC was decreased by a desentization of purinergic receptor by pretreatment of mATP, and the STC was decreased by pr,,creatment of reserpine (3 mg/kg, EP) 24 hours before experiments. Octreotide reduced the field stimulation induced contraction in the presence of mATP and of reserpinized muscle strips. The inhibitory effect of octreotide was more potent at 5 Hz than at 30 Hz. Octreotide did not affect basal ton and exogenous norepinephrine- or ATP-induced contraction. These results suggest that octreotide inhibit the contractility of the isolated rat vas deferens by inhibition of the release of neurotransmitters, both ATP and norepinephrine from adrenergic nerve terminal.
Adenosine Triphosphate ; Animals ; Baths ; Neurotransmitter Agents ; Norepinephrine ; Octreotide* ; Rats* ; Reserpine ; Vas Deferens*

The effect of the Nd:YAG laser on the rabbit retina was evaluated with fundus photography, light microscopy and transmission electron microscopy(TEM), and compared with the effect of the Argon laser. Fundus photography was performed at 2 days, 4 days, 7 days, 14 days, 29 days and 49 days after treatment. The enucleated retina was examined by light microscopy and TEM. In YAG treated eye, laser reaction was not found at 0.5mJ level but laser reaction(G2-3) was found at 1.5mJ level. Laser reaction(G3-4) with expulsive bleeding was found at 2.5 and 3.5mJ level. Bleeding was seemed to be originated from the choroidal layer. 2 days after treatment, hemorrhage was sustained but bleeding was not continued. 7 days after treatment, hemorrhage was completely absorbed. In Argon treated eye, photocoagulation burns was well formed without and bleeding. In pathologic examination of YAG treated eye, full thickness disruption of the retina amd Bruch's membrane and replacement of these layers with fibrous scar tissue were revealed at 2.5 and 3.5mJ level. In 1.5mJ energy level of the YAG laser and Argon laser irradiation, the outer half of the retina, RPE and Bruch's membrane appeared to be pridominantely affected than the inner half of the retina. The extent and character of his to pathology in Argon treated lesion was not so different from that of the YAG laser 1.5mJ lesion.
Argon ; Bruch Membrane ; Burns ; Choroid ; Cicatrix ; Hemorrhage ; Lasers, Solid-State ; Light Coagulation ; Microscopy ; Pathology ; Photography ; Retina*

This study aimed to investigate the existence of GABA receptor and the mechanisms of action of GABA and diazepam of the trachealis muscle isolated from dog. Horizontal muscle strips of 2mm×15mm were prepared from canine trachea, and isometric myography in isolated muscle chamber bubbled with 95/5%-O₂/CO₂ at 36℃, at the pH of 7.4 was performed. Muscle strips contracted responding to the electrical field stimulation (ESP) by 2~20 Hz, 20 msec, monophasic square wave of 60 VDC. GABA and diazepam suppressed the EFS-induced contractions to the similar extent, significantly. (p<0.05). Bicuculline, a GABA(A) receptor antagonist blocked both GABA- and diazepam-inhibitions; but DAVA, a GABA(B) receptor antagoinst did not affect either of them. These results suggest than in the canine trachealis muscle, there may be only GABA(A) receptor, and GABA and diazepam inhibit the contractility via GABA(A) receptor.
Animals ; Bicuculline ; Diazepam ; Dogs ; gamma-Aminobutyric Acid* ; Hydrogen-Ion Concentration ; Myography ; Receptors, GABA ; Receptors, GABA-A ; Trachea