Lidocaine Increases Intracellular Sodium Concentration through Voltage-dependent Sodium Channels in an Identified Lymnaea Neuron

Background: The local anesthetic lidocaine affects neuronal excitability in the central nervous system; however, the mechanisms of such action remain unclear. The intracellular sodium concentration ([Na+]i) and sodium currents (INa) are related to membrane potential and excitability. Using an identifiable respiratory pacemaker neuron from Lymnaea stagnalis, the authors sought to determine whether lidocaine changes [Na+]i and membrane potential and whether INa is related to these changes.

Methods: Intracellular recording and sodium imaging were used simultaneously to measure membrane potentials and [Na+]i, respectively. Measurements for [Na+]i were made in normal, high-Na+, and Na+-free salines, with membrane hyperpolarization, and with tetrodotoxin pretreatment trials. Furthermore, changes of INa were measured by whole cell patch clamp configuration.

Results: Lidocaine increased [Na+]i in a dose-dependent manner concurrent with a depolarization of the membrane potential. In the presence of high-Na+ saline, [Na+]i increased and the membrane potential was depolarized; the addition of lidocaine further increased [Na+]i, and the membrane potential was further depolarized. In Na+-free saline or in the presence of tetrodotoxin, lidocaine did not change [Na+]i. Similarly, hyperpolarization of the membrane by current injections also prevented the lidocaine-induced increase of [Na+]i. In the patch clamp configuration, membrane depolarization by lidocaine led to an inward sodium influx. A persistent reduction in membrane potential, resulting from lidocaine, brings the cell within the window current of INa where sodium channel activation occurs.     

Insulinoma: Selective arterial calcium injection performed to confirm localization and complete resection

A case of insulinoma is reported in a patient in whom selective arterial calcium injection (SACI) tests were performed both to confirm tumor localization before surgery and to confirm complete tumor removal during surgery. An 18-year-old woman with hypoglycemic episodes was diagnosed with an insulinoma in the pancreatic body demonstrated by celiac arteriography. In a preoperative SACI test, calcium was injected into the splenic artery (SpA), gastroduodenal artery (GDA), and superior mesenteric artery (SMA). Serum immunoreactive insulin (IRI) and proinsulin levels were measured in hepatic venous samples. IRI was markedly increased after the injection of calcium into the GDA and SMA, while there was no response in IRI levels when calcium was injected into the SpA. Therefore, no occult insulinoma was revealed in the distal area fed by the SpA, although the presence of insulinoma was uncertain in the proximal pancreas. In the intraoperative SACI test, calcium was injected into the celiac artery. Insulin (determined by enzyme immunoassay) and proinsulin levels were measured in portal venous samples before and after resection of the tumor. After resection, these levels decreased in response to the calcium stimuli, confirming complete removal of the insulinoma. The SACI test was helpful to localize the insulinoma and was useful to confirm the complete removal of the tumor.     

A case of aortitis syndrome complicated with amyloidosis, type AA]

We recently saw a patient who had aortitis syndrome associated with secondary amyloidosis. To our knowledge, she is the fourth report of this complication occurring in aortitis syndrome. In November 1985, the patient, a 18 year-old woman, was admitted to our hospital because of a high fever, back pain, abdominal pain and general fatigue. On physical examination, bruit was audible on the abdomen, bilateral radial artery was weakly palpable. Angiography showed the stenosis of bilateral carotid artery, subclavian artery, renal artery and superior mesenteric artery. From the above findings, she was diagnosed aortitis syndrome, and treatment was begun with prednisolone. However, she developed recurrently a high fever, chest pain, abdominal pain and exertional dyspnea. Laboratory findings at the active stage revealed the marked elevation of leukocytes, erythrocyte sedimentation rate and C-reactive protein. On her clinical course, the number of circulating thrombocytes was paralleled with the activity of the disease. On June 1988, she developed suddenly a high fever and severe pain of abdomen. Pathological findings of her stomach showed the deposition of amyloid protein A. Laboratory findings depicted the marked increment of thrombocytes, beta-thromboglobulin and platelet factor 4. These results suggest that circulating thrombocytes may play a role in product ion of amyloid protein.     

Reconstruction of the distal foot dorsum with a distally based extensor digitorum brevis muscle flap.

We have successfully applied a reverse flow island flap of extensor digitorum brevis muscle for coverage of tissue defects in the distal portion of the foot dorsum in 2 patients. This flap covered the metatarsophalangeal area well with cadaver limb dissection and seems useful to cover the defect in the distal foot dorsum.     

Heterogeneity of anticardiolipin antibody

The antibody to cardiolipin(ACA) was tested in patients with systemic rheumatic disease. The frequency of IgG ACA was 46/100(46.0%) in systemic lupus erythematosus(SLE). In other rheumatic disease, this was less than 20%. Significant correlation between the presence of IgG ACA and thrombosis and/or thrombocytopenia was found in patients with SLE. Eight sera containing high titered IgG ACA from lupus patients were selected for further inhibition study. Inhibitors were consisted of cardiolipin(CL), phosphatidyl(p-)serine, p-inositol, p-glycerol, p-ethanolamine, p-choline, ds-DNA, ss-DNA, fresh platelets(PLT)and fresh red blood cells(RBC). All sera were markedly inhibited by negatively charged phospholipids. In 4 sera(group B), there was moderate inhibition by ss-DNA, ds-DNA, PLT and RBC. In another 4 sera(group A), mild but significant inhibition was obtained by PLT alone. The number of platelet in group A was less than that in group B. There were some differences in inhibitory activity, suggesting heterogeneity of antibody to CL. It may be possible to speculate that heterogeneity of IgG ACA cause various combination of clinical features such as thrombocytopenia and thrombosis.     

Charting of daily weight pattern reinforces maintenance of weight reduction in moderately obese patients.

To maintain reduced body weight by behavioral therapy in moderately obese patients, body weight was measured four times daily and charted in a weekly graph. Seventy-two female patients with simple obesity were divided into two groups: 55 patients with appliance of charting of weight pattern (group-I), and 17 patients without the charting (group-II). The percentage of patients followed for 2 years was different between group-I (87%) and group-II (65%) during 2 years after completion of weight reduction therapy interviews (p less than 0.05). Forty-eight of group-I patients succeeded in decreasing their weight by 15.2 +/- 1.5 (mean +/- SEM) kg during the 6.5 +/- 0.8 months of the therapy interviews. They were followed up for 3.8 years with no rebound weight gain. Eleven patients in group-II also succeeded in decreasing their weight by 16.8 +/- 1.9 kg during 7.8 +/- 1.3 months but their body weight rebounded by 9.0 kg during the 2-year followup period. Twelve of 15 male patients with weight charting maintained reduced weight during 4.3 years. It was easier and more effective for obese patients to maintain weight graphs for the longer period than to record no weight graphs. Obese patients could themselves monitor irregular weight patterns produced by overeating and correct the irregularities in food intake and daily lifestyles. This seems to explain why the illustration of daily fluctuations of weight measurements was useful for long-term maintenance of weight reduction.     

Inhibition of inward rectifier K+ currents by angiotensin II in rat atrial myocytes: lack of effects in cells from spontaneously hypertensive rats.

We examined the effects of angiotensin II (Ang II) on inward rectifier K+ currents (IK1) in rat atrial myocytes. [125I]Ang II-binding assays revealed the presence of both Ang II type 1 (AT1) and type 2 (AT2) receptors in atrial membrane preparations. Ang II inhibited IK1 in isolated atrial myocytes with an IC50 of 46 nmol/l. This inhibition was abolished by the AT, antagonist RNH6270 but not at all by the AT2 antagonist PD123319. Treatment of cells with pertussis toxin or a synthetic decapeptide corresponding to the carboxyl-terminus of Gialpha-3 abolished the inhibition by Ang II, indicating the role of a Gi-dependent signaling pathway. Accordingly, Ang II failed to inhibit IK1 in the presence of forskolin, dibutyryl-cAMP or protein kinase A catalytic subunits. In spite of the increased binding capacities for [125I]Ang II, Ang II failed to affect IKI in cells from spontaneously hypertensive rats (SHR). AT, immunoprecipitation from atrial extracts revealed decreased amounts of Gialpha-2 and Gialpha-3 proteins associated with this receptor in SHR as compared with controls. The reduced coupling of AT, with Gialpha. proteins may underlie the unresponsiveness of atrial IK1 to Ang II in SHR cells.     

A case of retroperitoneal venous aneurysm]

A case of retroperitoneal venous aneurysm is reported. A 73-year-old woman was referred to us with the chief complaint of left abdominal mass. A giant abdominal mass was palpable and diagnostic imaging examination including ultrasound tomography, excretory pyelography, computed tomography, magnetic resonance imaging and angiography revealed a giant cystic mass encircled by calcification in the left retroperitoneal space. Operation for this cystic mass was performed under the preoperative diagnosis of a giant left renal cyst. During operation the mass was located between the left kidney and the left adrenal gland. Because it was difficult to separate the mass from the left kidney the mass was removed with the left kidney. The extirpated tumor measured 15.5 x 15.0 x 9.5 cm and contained old blood clots and red-yellow colored fluid. A histological examination revealed that the tumor wall was composed of smooth muscle and elastic fibers. Therefore, pathological diagnosis was retroperitoneal venous aneurysm. Retroperitoneal venous aneurysm is very rare. To our knowledge, this is the 8th case of retroperitoneal venous aneurysm reported in Japan.     

Retrograde thrombosis of feeding arteries after removal of arteriovenous malformations

Five cases of retrograde thrombosis of former feeding arteries after removal of an arteriovenous malformation (AVM) are reported. The clinical features of these patients were studied and compared to those of 71 patients without this complication. The following characteristics were found to correlate with retrograde thrombosis: 1) advancing age of the patient; 2) large AVM size; and 3) markedly dilated and elongated feeders. It is suggested that the slow flow in the former feeding arteries that was observed immediately after AVM removal and pathological changes in these vessels due to long-standing hemodynamic stresses contributed to the development of retrograde thrombosis. Neurological manifestations related to retrograde thrombosis were noted in three of the five cases. Although infrequent, this complication should be considered as a serious possibility following removal of an AVM.