[Eck fistula syndrome].
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Amino Acids, Branched-Chain↗
Biomedical subjects
M Fukasawa
Publications and source records attributed to M Fukasawa.
In vitro protective effects of nicorandil on hypothermic injury to immature cardiac myocytes: comparison with nitroglycerin.
The purpose of the present study was to evaluate the functional and biochemical effects of nicorandil and nitroglycerin on cardiac myocytes incubated under hypothermic conditions. Nicorandil is a coronary vasodilator with mixed nitrate-potassium channel agonist activity. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 197 medium. Myocytes (12.5 x 10(5) myocytes/flask) were then incubated at 4 degrees C for 24 hours in media containing various concentrations of nicorandil (NRD) or nitroglycerin (NTG). After hypothermic incubation, CPK and LDH were measured. The myocytes were cultured for an additional 24 hours at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the nicorandil group, 10(-4) M NRD showed a significant beating rate recovery compared to control (44.2% vs. 24.6%, respectively, as a percent of control; i.e., beating rate prior to hypothermic incubation). Nitroglycerin treatment had no effect on either beating rate recovery or release of CPK and LDH from myocytes. However, the release of CPK and LDH was significantly suppressed by 10(-4) M nicorandil compared to the control (10(-4) M NRD: 24.1, 257.2; control: 125.4 mIU/flask, 459.5 mIU/flask, respectively). Thus nicorandil showed an approximate two-fold recovery of myocyte functional activity after hypothermic incubation with only minor biochemical effects, and therefore may be suitable for cardiac preservation.
Animals↗
In vitro evaluation of phosphate, bicarbonate, and Hepes buffered storage solutions on hypothermic injury to immature myocytes.
In this study we evaluated cardiac myocyte viability and function under hypothermic conditions using three types of buffer solutions: phosphate buffer solution (PBS), Krebs-Henseleit bicarbonate buffer solution (KHB), and Hepes buffered minimum salt solution (MSS). As a control, normal saline solution (NSS) was used. Cardiac myocytes were isolated from neonatal rat ventricles. Myocytes (12.5 x 10(5) myocytes/culture flask) were then incubated at 4 degrees C for 6, 12, 18, and 24 hours in various buffer solutions. After each incubation time, CPK and LDH were measured. The myocytes were then incubated for an additional 24 hours at 37 degrees C to evaluate the recovery of the myocyte beating rate. Group MSS had a significantly better beating rate recovery than group NSS (control) after 18 hours (MSS, 32.7%, NSS, 0.0% of control; i.e., beating rate prior to hypothermic incubation). In contrast, group KHB showed a significantly lower recovery ratio than group NSS at 12 hours (41.0%, 78.8%, respectively), and the lowest recovery was observed in group PBS beginning at 6 hours of hypothermic incubation (27.6%). Group MSS significantly suppressed the release of CPK and LDH compared to group NSS at 24 hours (MSS, 246.7 and 440.2 mIU/flask; NSS, 369.7 and 821.3 mIU/flask, respectively). In contrast, groups PBS and KHB showed significantly increased CPK and LDH levels compared to group NSS after 12 hours (PBS, 388.6 and 721.4 mIU/flask; KHB, 340.5 and 540.5 mIU/flask; NSS, 91.5 and 222.7 mIU/flask, respectively). In conclusion, Hepes buffer has cytoprotective characteristics that may be suitable for long-term hypothermic preservation of immature myocardium compared to phosphate or bicarbonate buffer.
Animals↗
An in vitro evaluation of prostaglandin E1 and I2 on hypothermic injury to immature myocytes.
The purpose of this study was to evaluate the functional and biochemical effects of Prostaglandin E1 (PGE1) and prostaglandin I2 (PGI2) on cardiac myocytes incubated under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 107 medium. Following this, 12.5 x 10(5) myocytes/flask were incubated at 4 degrees C for 24 h in media with PGE1, at concentrations of 0 M (group E0), 10(-9) M (group E1), 10(-8) M (group E2), 10(-7) M (group E3), or 10(-6) M (group E4); or with PGI2 at concentrations of 0 M PGI (group I0), 10(-9) M (group I1), 10(-8) M (group 12), 10(-7) M (group I3), or 10(-6) M (group I4). After hypothermic incubation, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) were measured, and the myocytes were then cultured for 24 h at 37 degrees C to evaluate the recovery of the myocyte beating rate. Of the PGI2 groups, only group I2 recovered significantly more than the control group (group I0), at 47.9 +/- 28.5% (mean +/- SD) of the control, being the beating rate prior to hypothermic incubation, whereas it was 18.1 +/- 9.7% in group I0 (P < 0.025); however, there were no significant differences among the PGE1 groups. Moreover, the release of CPK and LDH was significantly suppressed in group 12 compared to the control, being 57.7 +/- 27.6 mIU/flask (P < 0.05) and 275.1 +/- 83.0 mIU/flask (P < 0.025), respectively, in group I2, and 96.8 +/- 38.3 mIU/flask and 439.6 +/- 147.1 mIU/flask in group I0. Again, no significant differences were observed among the PGE1 groups. In conclusion, PGI2 was found to have a direct cytoprotective effect on immature myocytes which suggests that PGI2 may promote cardiac preservation in the neonatal period.
Alprostadil↗
Possible deleterious effects of glucose on immature myocytes under hypothermic conditions.
The purpose of the present study was to evaluate the functional and biochemical effects of glucose-based solutions in combination with potassium or insulin (or both) on immature myocytes under hypothermic conditions. Myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 107 (University of Colorado solution). Initially, myocytes (12.5 x 10(5) myocytes/flask) were incubated at 4 degrees C for 6 hours in 5% glucose solution containing various potassium concentrations ranging from 0 to 80 mEq/L to evaluate the protective effects. Next, myocytes were incubated at 4 degrees C for 3, 6, 12, 18, and 24 hours in three types of solutions: normal saline solution (control), glucose-potassium solution, and glucose-insulin-potassium solution (glucose: 50 g/L; NaHCO3, 20 mEq; potassium, 20 mEq; insulin, 20 IU/L). After each incubation, creatine kinase and lactate dehydrogenase levels were measured in the incubation solutions. The myocytes then were cultured for an additional 24 hours at 37 degrees C to evaluate the recovery of myocyte beating rate. The 20-mEq potassium treatment showed significantly better beating rate recovery and lower enzymal release than the glucose-only control. The saline solution showed the best protection of all three solutions, both functionally and biochemically, by 12 hours. The greatest damage was observed with glucose-potassium solution, beginning at 3 hours of hypothermic incubation. Although potassium and insulin have additional protective effects on hypothermic preservation, the high concentration of glucose has noxious characteristics for immature myocytes that may not be suitable for cardiac preservation in the neonatal period.
Animals↗
Cytoprotective effects of nicorandil on hypothermic injury to immature cardiac myocytes--comparison with nitroglycerin, diltiazem and prostaglandin E1.
The purpose of this study was to evaluate the functional and biochemical effects of nicorandil (NRD), nitroglycerin (NTG), diltiazem (DTZ) and prostaglandin E1 (PGE) on cardiac myocytes incubated under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 107 medium. Myocytes (12.5 x 10(5) myocytes/flask) were then incubated at 4 degrees C for 24 h in media containing various concentrations of NRD, NTG, DTZ or PGE. After hypothermic incubation, creatine kinase (CK) and lactate dehydrogenase (LDH) were measured. The myocytes were cultured for an additional 24 h at 37 degrees C to evaluate the recovery of myocyte beating rate. In the nicorandil groups, 10(-4) M NRD showed a significantly increased beating rate recovery compared to the control (44% vs 25% respectively, as a percentage of the baseline values; i.e., beating rate prior to hypothermic incubation). Although treatment with 10(-6) M diltiazem showed no beneficial effects (10(-6) M; 25%, control; 30%), beating was not observed at all with 10(-4) M or 10(-5) M DTZ. There were no significant changes among the NTG and PGE groups. The release of CK and LDH was significantly suppressed with 10(-4) M NRD (10(-4) M: 24.1 mIU/flask, 257.2; control: 125.4, 459.5, respectively). In contrast, 10(-4) M DTZ showed significantly increased CK and LDH levels compared to its respective control (10(-4) M: 203.3 mIU/flask, 883.4; control: 112.3, 457.4, respectively). There were no significant differences in CK and LDH levels among the NTG and PGE groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Alprostadil↗
Effect of serum concentration on hypothermic preservation of cardiac myocytes isolated from neonatal rat ventricle.
The purpose of the present study was to evaluate the functional and biochemical effects of serum concentrations on hypothermic preservation of cardiac myocytes. Myocytes were isolated from neonatal rat ventricles and cultured for 4 days, and then incubated for 24 hrs at 4 degrees C in media containing 0, 2, 5, 10, and 20% fetal calf serum (FCS). The myocytes were then cultured for an additional 24 hrs at 37 degrees C to evaluate the recovery of myocyte beating rate. The recovery ratio of myocyte beating rate after hypothermic incubation was 25.3 +/- 14.2 percent of control in the serum-free, 33.0% in 2% FCS, 30.7% in 5% FCS, 22.3% in 10% FCS, and 24.3% in 20% FCS groups. Serum-free, 10% and 20% FCS groups had lower recovery ratios compared to the other two groups. The release of CPK and LDH after hypothermic incubation were similar in the serum-free, 2% and 5% FCS groups, however, significant increases were observed for the 10% and 20% FCS groups. It is suggested that fetal calf serum at high concentrations (> 10%) might be injurious to immature myocardium under hypothermic preservation, and that the optimum concentration of FCS is two percent or less.
Animals↗
Evaluation of immature cardiac myocyte viability after 24 hours of hypothermic preservation.
In this study, we evaluated cardiac myocyte viability and function under hypothermic conditions using three types of storage solutions; saline solution (SS), Euro-Collins solution (ECS) and MCDB 107 medium (MM). Cardiac myocytes were isolated from neonatal rat ventricles by collagenase dispersion and cultured for 4 days with MCDB 107 medium. A total of 12.5 x 10(5) myocytes/culture dish were used and the myocytes were incubated at 4 degrees C for 6, 12, 18 and 24 hrs in the various storage solutions. After each incubation time, CPK and LDH were measured in the storage solutions. The myocytes were then cultured in MCDB 107 medium and incubated for 24 hrs at 37 degrees C to evaluate the recovery of the myocyte beating rate. In group MM (n = 7), the recovery ratio of the myocyte beating rate was 99.2 percent of control (beating rate prior to hypothermic incubation) at 6 hours, 104.6% at 12 hrs and 44.8% at 24 hrs. Groups SS and ECS (n = 7 each) had significantly lower recovery ratios than the MM group (at 6 hrs: 74.3, 34.0; at 12 hrs: 61.0, 32.2; at 24 hrs: 0.0, 0.0 percent of control, respectively). Release of CPK and LDH in the MM group gradually increased and at 24 hrs was 28.6 IU/l and 93.6 IU/l, respectively. However, the SS group had significantly increased CPK and LDH values at 24 hrs (CPK: 66.9, LDH: 164.2). The ECS group showed the greatest increase in both markers (CPK: 317.5, LDH: 421.2). In summary, saline solution showed a beneficial effect on recovery of myocyte viability at 12 hours compared to Euro-Collins solution, however, MCDB 107 medium had the best overall protective effect on cultured myocytes. Accordingly, alternate hypothermic storage solutions, such as cell-culture medium, may have protective characteristics that are suitable for cardiac preservation.
Amino Acids↗
Synthesis and antibacterial activity of novel carbapenems with a catechol or hydroxypyridone moiety.
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Carbapenems↗
[Palliative surgery of congenital heart disease in early infancy].
A total of 38 patients aged under 3 months with congenital heart disease (CHD) underwent palliative surgery between April, 1988 and March, 1993. The mean age at operation was 28.0 (range 1 to 87) days. Palliative procedures were: pulmonary artery banding (PAB) in 14 patients (IAA complex: 4, CoA complex: 6, AVSD: 2, TA: 2), Blalock-Taussig shunt (BTS) in 12 (TOF: 2, TGA: 1, AVSD: 1, PA-IVS: 3, PA-VSD: 3, PA-SV: 1, PA-AVSD: 1), Brock operation in 6 (PPS: 2, PA-IVS: 3, PA-SV: 1), Blalock-Hanlon operation (BH) with PAB in 2 (MA-SV: 2) and Norwood operation (NRD) in 4 (HLHS: 4). PAB of IAA or CoA complex was performed just after the repair of IAA or CoA. Overall operative mortality was 23% (PAB: 14.3, BTS: 8.3, Brock: 33.3, NRD: 100%). One week after PAB, pulmonary artery pressure (PAP) decreased significantly compared to the intraoperative PAP value after PAB (43.1 +/- 16.2, 32.3 +/- 9.0 mmHg, p < 0.05, respectively). Pulmonary artery index (PAI), which is an index of pulmonary artery growth, after BTS increased significantly compared to the preoperative value (mean follow-up interval: 22.1 months) (379.5 +/- 101.4, 159.3 +/- 51.2, p < 0.001, respectively). During Brock operation, balloon catheter was used in order to dilate pulmonary valve. One year after Brock operation, mean pressure gradient through the pulmonary valve 22.6 mmHg. Two-staged corrections of CHD will be performed both safely and successfully by effective palliations at the first stages in early infancy.
Cardiac Surgical Procedures↗
[Tetralogy of Fallot with absent pulmonary valve: a successful case by total corrective surgery in 25 days old infant].
A 25 days old neonate of tetralogy of Fallot with absent pulmonary valve underwent total corrective surgery which consisted of VSD patch closure, resection of anterior wall of both pulmonary arteries and right ventricular outflow tract reconstruction using a monocuspid equine pericardial patch. Postoperatively, the right pulmonary artery diameter decreased from 17.8 mm (307%N) to 7.5 mm (129%N) and the left pulmonary artery diameter from 16.9 mm (338%N) to 8.3 mm (166%N). The patient was weaned from the ventilator 2 days after operation, whose post-operative course was uneventful. Total corrective surgery may provide a great success to symptomatic patients during the neonatal period.
Cardiac Surgical Procedures↗
[Clinical diagnosis of early breast cancer].
During the recent 5 years between 1988 and 1992, 254 cases of breast cancer were experienced in the Tsukuba University Hospital. Of them, 80 cases were palpable cancers measuring less than 2cm and 37 cases were nonpalpable cancers. The total of early cancers was 117 cases, 43.3% of all cases. Noninvasive carcinoma without minimally invasive carcinomas were 35 cases, 13.2% (ductal ca: 27, lobularca: 2, Paget ca: 6). According to the palpability of tumour mass, the sensitivity and accuracy rate of palpable early masses are 56.6% and 88.4% by physical examination, 57.9% and 96.4% by mammography, 77.6% and 82.5% by echography respectively. Those of nonpalpable diseases are 29.0% and 88.8% by physical examination, 42.9% and 91.2% by mammography, and 32.1% and 76.8% by echography. The sensitivity of echography for palpable breast cancer is extremely high. On the other hand, mammography is the most effective for nonpalpable cancer. For the detection of noninvasive carcinoma, characteristics of nipple discharge, measurement of CEA in nipple discharge and erosion of the nipple are other important factors.
Adult↗
[Etiology and management of esophageal varices].
The most common etiogenic disease of portal hypertension that we experience is liver cirrhosis, which accounts for 84% of all cases. In patients with portal hypertension, congestion by portal blood due to cirrhosis causes a rise in portal pressure and development of collateral circulation between the portal system and the postcaval system is observed. Esophageal varices are associated with higher mortality than any other symptom of portal hypertension and are an important consideration in treatment. When emergency endoscopic examination and diagnosis show esophageal variceal bleeding, the varices must be constricted directly using a Sengstaken-Brakemor tube. If hemostasis is maintained, medical and surgical procedures can be performed after the recovery of body strength. Endoscopic Injection Sclerotherapy (EIS) has recently been widely carried out to prevent variceal bleeding and its application is increasing. However, treatment with EIS alone is not sufficient in terms of long-term efficacy, and surgical treatment is effective, especially in patients with gastric varices or splenomegaly. For Child A and B groups, both with good liver function, non-shunting operation, especially, the SUGIURA procedure, shows a marked effectiveness on varices. For group Child C, EIS is selected. The newly-developed Transjuglar Intrahepatic Portasystemic Shunt (TIPS), is being used, recently. For hepatic insufficiency, liver transplantation is expected to be one of the method for future treatment. Cirrhosis is also commonly accompanied by hepatoma, and this must be taken into consideration in treatment.
Catheterization↗
Cardiac myocyte functional and biochemical changes after hypothermic preservation in vitro. Protective effects of storage solutions.
In this study, we evaluated cardiac myocyte viability and function under hypothermic conditions with four types of storage solutions, saline solution, Euro-Collins solution, University of Wisconsin solution, and MCDB 107 medium. Cardiac myocytes were isolated from neonatal rat ventricles by collagenase dispersion and cultured for 4 days with MCDB 107 medium. A total of 12.5 x 10(5) myocytes per culture dish was used and the myocytes were incubated at 4 degrees C for 6, 12, 18, and 24 hours in the various storage solutions. After each incubation time, creatine kinase and lactate dehydrogenase were measured in the storage solutions. The myocytes were then incubated for 24 hours at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the MCDB 107 group (n = 7), the recovery ratio of myocyte beating rate was complete by 12 hours, then decreased to 44.8% of control (beating rate before hypothermic incubation) at 24 hours. The saline, Euro-Collins, and University of Wisconsin groups (n = 7 each) had significantly lower recovery ratios than the MCDB 107 group (at 12 hours: 61.0%, 32.2%, and 48.9%; at 18 hours: 0.0%, 5.5%, and 15.1% of control, respectively). Release of creatine kinase and lactate dehydrogenase in the MCDB 107 group gradually increased and at 24 hours was 143.2 mIU/flask and 486.2 mIU/flask, respectively. However, the saline and University of Wisconsin groups had significantly increased creatine kinase and lactate dehydrogenase values at 24 hours (creatine kinase: 334.6 and 319.6 mIU/flask; lactate dehydrogenase: 821.6 and 654.4 mIU/flask, respectively). The Euro-Collins group showed the greatest increase in both markers (creatine kinase: 1587.5, lactate dehydrogenase: 2106.9 mIU/flask). In summary, saline and University of Wisconsin solutions showed a beneficial effect on recovery of myocyte viability at 12 hours compared with Euro-Collins solution, however MCDB 107 medium had the best overall protective effect on cultured myocytes. Accordingly, alternate hypothermic storage solutions, such as cell-culture medium, may have protective characteristics that are suitable for cardiac preservation.
Adenosine↗
Protection of cardiac myocytes from hypothermic injury by cardiac fibroblasts isolated from neonatal rat ventricle.
In this study, we evaluated the functional and biochemical effects of cardiac fibroblasts (CFs) on cardiac myocytes (CMs) incubated under hypothermic conditions. CMs and CFs were isolated from neonatal rat ventricles and cultures of myocytes only or myocytes in coculture with CFs were established. A CM and CF concentration of 2.5 x 10(5) cells/ml was chosen and the optimum proportion of CF was determined to be 33% (ml CM:ml CF) as follows: 6:0 (group C-a), 4:0 (group C-b), 4:2 (group M-F). On the fourth day of culture, cells were incubated at 4 degrees C for 6, 12, 18, 24, 36 and 48 hr. After each incubation, creatine phosphokinase ((PK) and lactate dehydrogenase (LDH) were measured in the medium, and then the cells were cultured for an additional 24 hr at 37 degrees C to evaluate the recovery of the CM contracting rate. In groups C-a and C-b (n = 6 each), the recovery ratio of CM contracting rate decreased at 18 hr (C-a, 59.0; C-b, 55.6% of control; i.e., contracting rate prior to hypothermic incubation), reaching null levels at 48 hr. However, group M-F (n = 6) showed a significantly increased recovery at 18 hr (95.7%, P < 0.05; at 48 hrs, 27.6%). Release of CPK and LDH in groups C-a and C-b increased gradually by 24 hr and showed a marked increase at 48 hr (C-a, 114.3 x 10(-2), 194.2 x 10(-2); C-b, 81.6 x 10(-2), 118.6 x 10(-2) IU/flask, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Prevention of postischemic reperfusion injury: the improvement of myocardial tissue blood flow after ischemia by terminal nicorandil-Mg cardioplegia.
We evaluated the preventive effect of postischemic reperfusion injury by Nicorandil-Mg cardioplegia given just prior to reperfusion as "terminal cardioplegia." Twenty seven dogs were placed on cardiopulmonary bypass and the aorta was cross-clamped for 90 min under hypothermic (17-19 degrees C) cardioplegic arrest. The canine hearts were divided into three groups: in group A (n = 10) the hearts reperfused without any treatment; in group B (n = 9) the hearts received coronary perfusion with Nicorandil-Mg solution (Nic, 8 mg/l; Mg, 20 mEq/l; glucose, 50 g/l) for 2 min just prior to reperfusion; and in group C (n = 8) the hearts received coronary perfusion with Nicorandil-Mg free solution (glucose, 50 g/l). During and after ischemia, the myocardial tissue PCO2 (t-PCO2) was continuously monitored by an ion-sensitive field effective transistor (ISFET) sensor. In addition, the myocardial tissue blood flow (TBF), oxygen consumption, and lactate flux were then calculated at 5, 10, 20, and 40 min of reperfusion. In the initial reperfusion period, Group B showed an improved TBF compared to group A and C (at 5 min, group B was 42.7 +/- 11.9; group A was 29.4 +/- 11.2, P < 0.025; and group C was 33.9 +/- 9.2% of the preischemic control level, P < 0.05). T-PCO2 in group B was significantly decreased at 5 min of reperfusion (group B, 127.5 +/- 22.5-->42.5 +/- 9.7; group A, 117.5 +/- 23.0-->85.2 +/- 17.4, P < 0.001; group C, 122.3 mmHg-->68.2 +/- 18.7 mmHg, P < 0.01), and group B had a better metabolic recovery.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
A cardiac myocyte culture system as an in vitro experimental model for the evaluation of hypothermic preservation.
In cardiac transplantation, the donor heart is exposed to severe hypothermic and ischemic conditions. The purpose of the present study was to evaluate the functional and biochemical effects on cardiac myocytes cultured under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days, then incubated (1.5 x 10(6) myocytes/culture flask) for 24 h in media at 4, 10, 15, 20, and 37 degrees C. In addition, myocytes were incubated at 4 degrees C for 6, 12, 18, 24, 36, and 48 h. After each incubation, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) were measured and the myocytes then cultured for an additional 24 h at 37 degrees C to evaluate the recovery of the myocyte beating rate. The recovery ratio of the myocyte beating rate following 24 h of varying temperature incubations was complete for the 10, 15, 20, and 37 degrees C groups, although it was markedly decreased in the 4 degrees C group, at 25.1% of the control; taken as the beating rate prior to hypothermic incubation. The release of CPK and LDH in the 4 degrees C group showed a three-fold increase compared to the other four groups, with a CPK of 147.2 mIU/flask and a LDH of 487.5 mIU/flask. The recovery of the beating rate for varying time incubations at 4 degrees C was complete for the 6- and 12-h groups, but decreased significantly in the other four groups, being 59.0% at 18 h, 28.2% at 24 h, 16.3% at 36 h, and 0% at 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
In vitro evaluation of diltiazem on hypothermic injury to immature myocytes.
The purpose of the present study was to evaluate the functional and biochemical effects of diltiazem (DTZ) on cardiac myocytes incubated under hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days with MCDB 107 medium. Then, myocytes (12.5 x 10(5) myocytes/flask) were incubated at 4 degrees C for 24 hours in media with or without DTZ at concentrations of 0 M (group C), 10(-7) M (Group D1), 10(-6) M (group D2), 10(-5) M (group D3), or 10(-4) M (group D4). After 24 hours at 4 degrees C, CPK and LDH were measured. The myocytes were then cultured for 24 hours at 37 degrees C to evaluate the recovery of the myocyte beating rate. In group C (n = 7), the recovery ratio of the myocyte beating rate was 29.9% of control (beating rate prior to hypothermic incubation). Groups D1 and D2 (n = 7 each) had approximately the same recovery ratios as group C (24.0% and 24.7%, respectively); however, groups D3 and D4 (n = 7 each) showed no beating rate recovery. Release of CPK and LDH in group C was 112.3 mIU/flask and 457.4 mIU/flask, respectively. Groups D1 and D2 showed no significant differences in both enzymes compared to group C. However, the levels of CPK were significantly higher in group D4 (203.3, p < 0.05), and LDH levels were significantly higher in groups D3 and D4 (669.3, p < 0.05; 883.4, p < 0.02). In conclusion, DTZ showed no protective effects on hypothermic injury to immature cardiac myocytes; moreover, it accelerated cellular injury at the concentrations of 10(-5) and 10(-4) M both functionally and biochemically. Therefore, diltiazem may not be suitable for cardiac preservation during the neonatal period.
Animals↗