Recent electrophysiological data have provided the evidences that background currents such as Na(+)-Ca2+ exchange can significantly modulate cardiac pacemaker activity. In this study, the effects of extracellular Na+ and Ca2+ concentrations on the pacemaker activity were investigated by measuring the intracellular Na+ activity (aiNa) with Na(+)-selective microelectrodes and the results are summarized as follows. 1) In the rabbit SA node, aiNa was 3.2 +/- 0.3 mM and mean MDP (maximal diastolic potential) was -63.3 +/- 1.4 mV. 2) Graded decreases of external Na+ concentration resulted in the loss of spontaneous beating, hyperpolarization and the decrease of aiNa. 3) An increase in extracellular Ca2+ concentration in low Na+ solution augmented the transient decrease of aiNa, about 3 minutes in low Na+ solution, until aiNa started to increase. 4) In low Na+ solution, which had extracellular Ca2+ concentration according to the calculation based on the equilibrium state of Na+-Ca2+ exchange, aiNa was continuously decreased. It was concluded that intracellular Na+ activity modulated by Na+-Ca2+ exchange could play an important role in the initiation of pacemaker potential.
Action Potentials ; Animal ; Biological Transport ; Calcium/*metabolism/physiology ; Electrophysiology ; Female ; Male ; Pacemaker, Artificial ; Rabbits ; Sinoatrial Node/*metabolism/physiology ; Sodium/*metabolism/physiology ; Support, Non-U.S. Gov't

Dose-related depression of left ventricular function or cardiac output has been reported in humans and in vivo animal studies with sevoflurane (SEVO) anesthesia and myocardial depressant effect of SEVO appeared to be comparable to that produced by isoflurane (ISO). This study was designed to determine the mechanical and electrophysiologic mechanism of the direct negative inotropic effects of SEVO. The effects of SEVO were comprared to those produced by equipotent concentration of ISO in the same isolated myocardial preparations. Isometric force of isolated guinea pig ventricular papillary muscle was studied in normal and 26 mM K+ Tyrode's solution. Rat papillary muscle was also used to evaluate the effect on Ca2+ release from the sarcoplasmic reticulum (SR) at low stimulation rates. Muscles were bathed at 36-37 degrees C in normal K Tyrode's solution bubbled with 95% O2/ 5% CO2 (pH 7.4) and were electrically stimulated following rest and at rates up to 3 Hz. Normal and slow action potentials were evaluated by using conventional microelectrodes. Muscles were also subjected to rapid cooling (from 37 degrees C to 2 degrees C) in order to elicit a transient rapid cooling contracture (RCC) known to be activatel by Ca2+ content released from the SR. RCCs were elicited after 2 Hz stimulation, which produced an RCC tension similar to that of the preceding contraction in control. SEVO and ISO were administered by dial setting in each vaporizer at 1.7 (1 MAC) and 3.4% (2 MAC), and 1.15 (1 MAC) and 2.3% (2 MAC), respectively. 20% and 40% depression of contractility was shown at 1.7 and 3.4% concentration of SEVO and the extent of depression was similar to equipotent concentration of ISO from rested state up to 3Hz stimulation rates. 1 and 2 MAC concentrations of SEVO (1.7 and 3.4%) or ISO (1.15% and 2.3%) in normal K+ Tyrode's solution caused dose-related depression of peak force at low stimulation rates (RS, 0.1, and 0.5 Hz). Although the normal action potential (AP) amplitude or Vmax were not changed, APD50 and APD90 were prolonged characteristically at 2 MAC of both anesthetics. Whereas no contractile depression was shown at RS and 0.1 Hz stimulation rates in rat papillary muscles, significant depression was noted from 0.5 to 3 Hz in 3.4% SEVO or 2.3% ISO. In the partially depolarized (26 mM K+ Tyrode's solution) beta-adrenergically stimulated myocardium, 2 MAC concentration of both anesthetics caused selective depression of late peak in the biphasic contraction without changing early peak. In slow AP, 3.4% SEVO or 2.3% ISO did not cause any change in AP amplitude and Vmax whereas APD50 and APD90 were prolonged as in Normal APs. Rapid cooling preceded by 15 min rest showed little contractile force and marked prolongation of the time to peak contracture with almost complete absence of contracture after 2Hz stimulation rates following 3.4% SEVO or 2.3% ISO. Although complete recovery of peak force could be observed, little restoration of RCC was shown after washout for 15 minutes at 2 MAC concentration of both anesthetics characteristically. The effect of SEVO on isolated myocardial contraction was similar to that of ISO. While neither anesthetic depressed the rapid initial Ca+ release from the SR, the depression of RCC and late tension suggest an alteration in some SR pathway. The direct myocardial depressant effects of SEVO and ISO are likely to be related to depressed Ca2+ influx through the cardiac memebrane, while AP prolongation may be due to actions on K+ currents.
Action Potentials ; Anesthesia ; Anesthetics ; Animals ; Baths ; Cardiac Output ; Contracture ; Depression ; Guinea Pigs ; Humans ; Isoflurane* ; Microelectrodes ; Muscles ; Myocardial Contraction ; Myocardium ; Nebulizers and Vaporizers ; Papillary Muscles ; Rats ; Sarcoplasmic Reticulum ; Ventricular Function, Left

Ryanodine has different effects on the contractility of rat and guinea pig ventricular muscle. Thus we investigated the effect of ryanodine on the intracellular Ca2+ and Na+ activities of the rat and guinea pig ventricular myocytes with two specific aims; whether there are any differences in intracellular Na+ activities between rat and guinea pig ventricular muscle cells, and if any, how the differences in intracellular Na+ activities are related to the effect of Na(+)-Ca2+ exchange on the action potential configuration and excitation-contraction coupling of the rat and guinea pig ventricular myocytes. Ryanodine (10(-7) M) diminished the slow repolarization phase of the rat ventricular action potential while the duration of the rapid repolarization phase increased. Ryanodine (10(-7) M) significantly increased the plateau of the action potential. At the steady state of 0.2 cps, intracellular Na+ activities (aiNa) of the rat and guinea pig ventricular myocytes were 8.7 +/- 5.2 mM (n = 16, 4 rats) and 10.0 +/- 4.1 mM (n = 25, 7 guinea pigs) respectively, but there were no statistically significant differences. The contractility of the rat ventricular muscle nearly disappeared due to ryanodine (10(-7) M) with little changes in aiNa. Monensin (10 mM) not only increased the resting tension but also remarkably increased aiNa from 2.0 mM to 20 mM. Ryanodine (10(-7) M) continuously decreased aiNa of the guinea pig ventricular muscle after the contraction ceased to decrease. Monensin increased the contractility as well as aiNa. These results suggest that the contractility of rat and guinea pig ventricular myocytes is determined by the change in the action of the Na(+)-Ca2+ exchange mechanism depending upon the plateau of action potential and the intracellular Na+ and Ca2+ activities. So ryanodine could decreases the contractility via its effect on Na(+)-Ca2+ exchange transport which could be one of possible mechanisms of negative inotropism by ryanodine.
Action Potentials/drug effects ; Animal ; Female ; Guinea Pigs ; Heart/*drug effects ; Heart Ventricle ; Intracellular Membranes/metabolism ; Male ; Myocardial Contraction/*drug effects ; Myocardium/cytology/*metabolism ; Rats ; Ryanodine/*pharmacology ; Sodium/*metabolism ; Support, Non-U.S. Gov't

Clinical observations were made on the injuries of the genito-urinary tract of the in-patients in the Department of Urology, Kyungpook National University Hospital during the period from January, 1971 to December, 1975. The results were as follows. Of 732 Cases hospitalized, 180 cases were injury of the genitourinary tract, giving a rate of 24. 6%. Most favorable age was in from 20 to 39 years for about 50%. The sex ratio, male to female, was 5.4 : 1. The urethra was involved most frequently (32.5%), the external genitalia in 20.4 %, the bladder in 13.6 % and the ureter in 3.7%. Traffic accident was the most frequent cause of the injury (36.1%) and the next was kick and blow, fall from a height etc. In detail, traffic accident was the most frequent cause of the renal, bladder and urethral injuries. The most ureter injury was iatrogenic. The kick and blow was the most frequent cause of the injuries of the external genitalia. Contusion was the most frequent type of 57 renal injuries (35 cases). On observations of 57 renal injuries, 41 cases were treated conservatively, and operation was performed in 16 cases (nephrectomy 10, partial nephrectomy 4, renorrhaphy 2.). In 26 bladder injuries, extraperitoneal type (15 cases) was more than the intraperitoneal type (11 cases). 10 cases were associated with pelvic bone fracture (38. 5%), On 28 cases out of 62 urethral injuries were associated with pelvic bone fracture (45.2%).
Accidents, Traffic ; Contusions ; Female ; Genitalia ; Gyeongsangbuk-do ; Humans ; Male ; Nephrectomy ; Pelvic Bones ; Sex Ratio ; Ureter ; Urethra ; Urinary Bladder ; Urology

PURPOSE: To identify the changes of bony landmarks with rotation and to compare the reliability and accuracy of Perdriolle's method before and after training on the exact bony landmarks. MATERIALS AND METHODS: Simple A-P radiographs were taken with rotation from 5 degree to 50 degree at 5 degree interval using 10 dry human vertebrae (2 sets of T3, T6, T9 8 L3) with no bony abnormality. Axial rotation was measured before and after training on the exact bony landmarks by three observers, twice for each radiographs. Repeated measures of ANOVA were used for inter- < intraobserver variance and regression analysis for root mean square error and deviation of differences. RESULTS: Mamillary process, inner margin of lamina, proximal and distal costovertebral joints, upper margin of concave pedicle and tip of the transverse process on the convex side confused the exact outline of the pedicle, while neural foraminal margin was helpful in identifying the location of the indistinct convex pedicle and concave vertebral border. Of the 660 measurements before and after training 372 and 397 errors were made, respectively, of which 88.9% and 88.5% were within +/-5 degree(P > 0.05). Incidence of error greater than 5 degree was high at upper thoracic vertebra and 20 degree-40 degree of rotation regardless of training. The effects of training, however, was greatest at T3 and 20 degree-40 degree of rotation. Inter- < intraobserver variance was diminished at T3 and at the rotation between 20 degree-40 degree after training. CONCLUSIONS: We could conclude that training on the exact bony landmarks did not reduce the overall error incidence. Accuracy and reliability, however, was increased at T3 after training and the efficacy of training was more evident in moderate vertebral rotation than in small or large vertebral rotation.
Humans ; Incidence ; Joints ; Spine

Bone formation by osteoblast may be closely related to the increase in intracellular Ca2+ activity of osteoblast. In order to study the effects of changes in Ca2+ activity of osteoblast-like cell on fracture healing, we changed intracellular Ca2+ activity of osteoblast-like cells by vanadate and verapamil. And the process of fracture healing was observed after injection of the treatment osteoblast-like cells into the fracture site by hematoxylin-eosin (H-E) stain and bromodeoxyuridine (BrdU) stain. The results were as follow: 1) The most effective range of concentration which could facilitate bone formation was 10-6 to 10-5 M. 2) H-E stain showed more abundant osteoblast and osteoid tissues, more active mitotic division of osteoblast, and earlier appearance of chondroblast and chondroid tissue, making the maturation of woven bone faster in the vanadate-treated group than in the control group. The opposite was true in the verapamil-treated group compared with the control group. 3) BrdU labeling index showed more active osteoblastic proliferation in the vanadate-treated than in the control group. The opposite was observed in the verapamil-treated group compared with the control group. From these results, the fracture healing appears to be facilitated and decelerated by vanadate which apparently increase intracellular Ca2+ activity of osteoblast and verapamil which decreases it, repectively. Therefore the change of intracellular Ca2+ activity of osteoblast can be considered to be one of fracture healing mechanisms and expected to be applied for clinical purpose.
Bromodeoxyuridine ; Chondrocytes ; Fracture Healing ; Osteoblasts ; Osteogenesis ; Vanadates ; Verapamil

An unusual case of tumor arising in huge vesical diverticulum combined with benign prostatic hyperplasia in a 63 year old male is presented with brief review of literatures.
Diverticulum* ; Humans ; Hyperplasia* ; Male ; Middle Aged ; Prostate* ; Prostatic Hyperplasia ; Urinary Bladder

The removal of Ca2+ from the cardioplegic solutions could cause the danger of inducing a "calcium paradox" during reperfusion. Since intracellular Ca2+ activities are coupled to Na+ activities via Na(+)-Ca2+ exchange, an increase in intracellular Na+ activities during the cardioplegia could cause an abrupt Ca2+ influx when reperfused. To study the effects of Na+ and Ca2+ concentrations in cardioplegic solutions on intracellular Ca2+ activities during the cardioplegia and subsequent recovery period, the membrane potential and intracellular Na+ and Ca2+ activities of guinea pig ventricular papillary were measured. 1) A cardioplegia with low Ca2+ cardioplegic solution significantly decreased the overshoot and duration of the first action potential after cardioplegia, but the changes in action potential configuration were minimized after a cardioplegia with Ca2+ concentration adjusted according to the Na(+)-Ca2+ exchange mechanism. 2) Intracellular Na+ activity was continuously decreased during the cardioplegia, and the intracellular Na+ activity 20 minutes after cardioplegia was the highest with low Ca2+ cardioplegic solution. 3) Intracellular Na+ and Ca2+ activities were continuously decreased during the cardioplegia with Ca2+ concentration adjusted according to the Na(+)-Ca2+ exchange mechanism. 4) During a reperfusion of Tyrode solution after cardioplegia intracellular Na+ and Ca2+ activities were increased. Intracellular Ca2+ activity was increased more rapidly than intracellular Na+ activity. 5) The rate of increase in intracellular Ca2+ activity with reperfusion of Tyrode solution was dependent upon intracellular Na+ activity during cardioplegia, in such a way that the higher the intracellular Na+ activity was, the faster the intracellular Ca2+ activity increased. These data suggest that Na(+)-Ca2+ exchange mechanism may play an important role in the regulation of intracellular Ca2+ activity during recovery after cardioplegia.
Animal ; Calcium/*pharmacology ; Cardioplegic Solutions/*pharmacology ; Ions ; *Myocardial Reperfusion ; Osmolar Concentration ; Papillary Muscles/cytology/*drug effects ; Sodium/*pharmacology ; Solutions/pharmacology

Intracellular recordings in cerebellar slice preparation showed that applications of 4-AP altered the pattern of oscillatory firing activity in Purkinje cells (PCs), especially yielding pronounced changes in action potential shape. 4-AP increased the amplitude and duration of action potential significantly and decreased the spike frequency. After 4-AP application, the duration of bursting was prolonged and the duration of after-burst hyperpolarization was progressively shortened. In all PCs tested, the rhythmicity of oscillatory firing activity was abolished completely at the steady state. These results suggest that 4-AP-sensitive currents determine the shape and frequency of individual Ca(2+)-dependent action potentials as well as maintaining oscillatory firing activity in PCs.
4-Aminopyridine/pharmacology* ; Action Potentials/drug effects* ; Animal ; Calcium/physiology* ; Electrophysiology ; In Vitro ; Oscillometry ; Purkinje Cells/physiology* ; Purkinje Cells/drug effects* ; Rats ; Rats, Sprague-Dawley

Using lipid bilayer reconstitution technique, we investigated the oxidation effect of t-butyl hydrogen peroxide (tBHP) on the single channel activity of the sarcoplasmic reticulum (SR) calcium release channels isolated from canine latissimus dorsi muscles. When 0.7% tBHP was added in the cytosolic side, the channel activity became suppressed (n = 7), and it was recovered by changing the solution to the control solution. The suppression was due to the change in the gating mode of the channel: before tBHP the channel opened to four sub-conductance levels, but it opened to only one level after tBHP. These effects by tBHP were different from the previous finding using hydrogen peroxide (H2O2), which may be explained by different oxidation patterns between the two oxidants.
Animal ; Calcium Channels/drug effects* ; Dogs ; Hydrogen Peroxide/pharmacology ; Peroxides/pharmacology* ; Sarcoplasmic Reticulum/metabolism ; Sarcoplasmic Reticulum/drug effects* ; tert-Butylhydroperoxide