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

No abstract available.
Humans

No abstract available.

PURPOSE: The purpose of this study is to evaluate the findings of magnetic resonance imaging(MRI) of posterior fossa hemangioblastoma and usefulness of contrast enhancement with Gd-DTPA. MATERIALS AND METHODS: Seven patients with posterior fossa hemangioblastoma were studied with both pre- and post-enhanced MRI. The MR images were reviewed regarding the location, size, signal intensities of cysts and mural nodules, and their contrast enhancement pattern. RESULTS: Five tumors were located in cerebellar hemisphere, one in vermis, and one in posterior part of medulla. One patient with von HippeI-Lindau disease had a medullary hemangioblastoma with multiple pancreatic cysts. In 6 cases, the major portion of the tumor was cysts and had small mulkal nodules. The solid portion was relatiely lange in one case, cemprising half of the tumor Cysts were oval shaped and their sizes were 3--6.7cm in diameter. In five cases(71%), septations were noted within the cysts. Cysts were isointense or slightly hyperintense on Tl-weighted image and hyperintense on T2-weighted image compared with cerebrospinal fluid. Mural nodules were oval or rounded appearance in five cases and flattened appearance in two, and their size was 0.5--2.5cm in diameter. Mural nodules were isointense to gray matter. They were detected in five cases on Tl-weighted images and one case on T2-weighted images. In two cases, vascular signal void area was noted in mural nodules. On contrast-enhanced Tl-weighted images, all mural nodules were intensely enhanced. CONCLUSION: MRI proved to be a good diagnostic method to detect and characterize posterior fossa hemangioblastoma. The most common finding is Cystic posterior fossa lesion with enhancing mural nodule. Contrast enhancement is essential for specific diagnosis.
Cerebrospinal Fluid ; Diagnosis ; Gadolinium DTPA ; Hemangioblastoma* ; Humans ; Magnetic Resonance Imaging* ; Pancreatic Cyst

As one of many cell-many cell-based cartilage repairing methods, transplantation of chondrocyte-embedded-collagen gels in cartilage defect was performed for more satisfactory regeneration of cartilage. The authors performed this study to investigate whether the TGF-beta1 treatment of chondrocytes can do some additional synergistic effect on the transplantation of chondrocyte-embedded-collagen gels for crtilage repair. Chondrocytes were isolated from the articular cartilage of newborn Sprague-Dawley rats. Chondrocytes cultured for 10 days in monolayer were embedded in the 0.45% type I collagen gel. Full-thickness cartilage defect was made in the patellar groove of adult Sprague-Dawley rats. Chondrocytes culdefect was made in the patellar groove of adult Sprague-Dawley rats. The cartilage defects were treated with the following methods in a total of 200 animals, which were assigned to 5 different groups of 40 rats. In the control group, the deffect was left without any treatment, in group I, the defect was filled with collagen gel only, in group II, with collagen gel coontaining 10 ng/ml concentration of TGF-beta1, in group III, with collagen gel containing chondrocytes, and in group IV, with collagen gel containing chondrocytes and TGF-beta1. At 1, 2, 4, 8, 12 weeks after the operation, eight rats of each group were sacrificed, and their distal femurs were harvested for the histologic and biomechanical tests. The section s were stained with hematoxilin and eosin. Alcian-blue, and Safranin-O. Regenerated cartilage was analyzed by the semiquantitative histological grading system. Point indentation test was performed as a biomechanical evaluation, and the stiffness was calculated. The results of the histological grading system revealed that the scores gradually increased with time in all groups, and the scores of group III and IV were higher than those of control, group I and II. The biomechanical study showed that the stiffness gradually increased to reach a plateau level in each group. In control, group I and II, the stiffness increased up to the eighth week and remained around the increased level at the twelfth week, and did not show any statistically significant difference between the groups. In group III and IV, the stiffness was higher than in control group, and increased markedly at the fourth week and the increased level was maintained onwards. The results of this study showed that the transplantation of chondrocyte-embedded-collagen gels enhanced the healing process, and the treatment of TGF-beta1 demonstrated at least partially significant improvement.
Adult ; Animals ; Cartilage ; Cartilage, Articular* ; Chondrocytes ; Collagen ; Collagen Type I ; Eosine Yellowish-(YS) ; Femur ; Gels ; Humans ; Infant, Newborn ; Rats* ; Rats, Sprague-Dawley ; Regeneration ; Transforming Growth Factor beta1

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*

No Abstract Available.

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*