To identify the presence of inwardly rectifying K+ channels and its characteristics, membrane currents were measured using a whole-cell patch clamp from isolated gastric myocytes of guinea-pig. Change of external K+ concentration from 5 to 90 mM induced an inward current at a holding potential of 80 mV. The high K+-induced inward current was blocked by Ba2+ and Cs+, but not by glibenclamide. With 90 mM K+ in bath, the Ba2+- and Cs+-sensitive currents showed strong inward rectification. Ten mM TEA weakly blocked the inward current only at potentials more negative than 50 mV. With 90 mM K+ in bath, hyperpolarizing step pulses from 10 mV induced inward currents, which were inactivated at potentials more negative than 70 mV. Reduction of external K+ to 60 mM decreased the amplitudes of the currents and shifted the reversal potential to more negative potential. The inactivation of inward K+ current at negative clamp voltage was not affected by removing external Na . These results suggest that the inwardly rectifying K+ channels may exist in gastric smooth muscle.
Baths ; Glyburide ; Membranes ; Muscle Cells* ; Muscle, Smooth ; Tea

The spontaneous contractions of gastric smooth muscles are regulated by slow waves, which are modulated by both nervous system and humoral agents. This study was designed to examine the effects of Prostaglandin E2 (PGE2) on the contractile and electrical activities of antral smooth muscles in guinea-pig stomach, using an intracellular recording technique. To elucidate the underlying mechanism for its effect on contractility, ionic currents were also measured using a whole-cell patch clamp method. The basal tone by PGE2 was variable, whereas the magnitude of phasic contractions was reduced (19.0 +/- 2.1%, n=19). The resting membrane potentials were hyperpolarized (-4.4+/-0.5 mV, n=10), and plateau potentials were lowered (-2.9+/-0.5 mV, n=10). In most cases, however, the initial peak potentials of slow waves were depolarized more by PGE2 than those of control. The frequency of the slows wave was increased from 5.7+/-0.2 cycles/min to 6.5+/-0.2 (n-22). Voltage-operated Ca2+ currents were decreased by PGE2 (n=5). Voltage-operated K+ currents, both Ca-dependent and Ca-independent, were increased (n-5). These results suggest that PGE2 plays an important role in the modulation of gastric smooth muscle activities, and its inhibitory effects on the contractility and activities of slow waves are resulted from both decrease of Ca2+ currents and increase of K+ currents.
Dinoprostone* ; Membrane Potentials ; Muscle, Smooth ; Nervous System ; Stomach*

PURPOSE: Diabetes mellitus is a chronic disorder and strict glycemic control, which cannot be successfully obtained without behavior modification, is the most important factor in prevention and management of complications. The purpose of this study was to investigate the short-term effects and associated factors of the diabetes education program and to assess the necessity of regular and structured education and support in diabetic children and adolescents. METHODS: Thirty patients (10.0-18.9 years) with type 1 diabetes mellitus (T1DM), attending the diabetes clinic in Seoul National University Children's Hospital, were included in the diabetes education program with intensified treatment. A six-day-course program was provided by a diabetes care team with doctors, a specialist diabetes nurse, a clinical dietitian, and a social worker. Patient data of disease duration and complication studies at the time of enrollment were reviewed and changes in HbA1c levels before and after the education program were analyzed. RESULTS: In 28 of 30 patients, significant decrease of average HbA1c levels (average 0.9%, median 0.8%, P < 0.001) was observed after education. The changes in average HbA1c levels were prominent in patients who were educated for the first time. On follow-up, HbA1c level at 3 months was significantly decreased (P = 0.009) but after 9 months, it tended to increase again. The decrease of average HbA1c levels after education was negatively correlated with disease duration (r = -0.60, P = 0.001). CONCLUSION: The short-term effect of the diabetes education program with intensified treatment in diabetic children and adolescents was optimistic but regular education and support in these patients should be sustained.
Adolescent ; Behavior Therapy ; Child ; Diabetes Mellitus ; Diabetes Mellitus, Type 1 ; Follow-Up Studies ; Humans ; Social Workers ; Specialization