Biomedical subjects

K Tagawa

Publications and source records attributed to K Tagawa.

201 records · Page 12Linked to original sources

PubMedDate not supplied

Myocardial energy metabolism in preserved heart: comparison of simple storage and hypothermic perfusion.

Isolated canine hearts were preserved for 24 hours by either simple hypothermic storage in Collins' M solution (group 1, n = 7) or hypothermic perfusion with oxygenated modified Krebs solution (group 2, n = 7), followed in both cases by reperfusion with cross circulation. Myocardial biopsies taken consecutively during preservation and after reperfusion were analyzed for high energy phosphates (adenosine triphosphate [ATP], adenosine diphosphate [ADP], adenosine monophosphate [AMP], and creatine phosphate), their catabolites (inosine), and lactate. In group 1, ATP decreased from 23.7 +/- 2.8 mumol/gm dry weight (mean +/- standard deviation) at 0 hours to 5.6 +/- 2.8 mumol/gm dry weight at the end of preservation. Creatine phosphate decreased and lactate increased significantly during 24 hours of preservation. The consumption rate of ATP appeared to have decreased after 18 hours of preservation. In group 2, ATP, creatine phosphate, and lactate remained at control levels during preservation. Coronary vascular resistance, however, increased significantly. After reperfusion functional measurements of the hearts in both groups did not vary significantly, despite the difference in myocardial ATP content (11.2 +/- 4.9 mumol/gm dry weight in group 1 and 17.9 +/- 3.9 mumol/gm dry weight in group 2; p less than 0.05). Simple hypothermic storage manifested a limitation in terms of energy store compared with hypothermic perfusion, whereas the latter appeared to have a risk of possible myocardial damage caused by the perfusion itself.

Animals↗

PubMedDate not supplied

Remote effects in MCA territory ischemic infarction: a study of regional cerebral blood flow and oxygen metabolism using positron computed tomography and 15O labeled gases.

Using positron computed tomography (PCT) and the 15O labeled gas steady-state inhalation technique, regional cerebral blood flow (rCBF), cerebral oxygen consumption (rCMRO2), and oxygen extraction fraction (rOEF) can be measured quantitatively in humans. We quantitatively examined the relationship between focal ischemic lesions and intact regions as detected by X-ray CT in such areas as the territory of the contralateral middle cerebral artery (MCA), thalami, pons, and cerebellar hemispheres. Twenty-three PCT measurements in 13 patients with unilateral ischemic infarction in the MCA territory as detected by X-ray CT were performed. Remote effects from cerebral infarction of the MCA territory were observed in the contralateral MCA territory, ipsilateral thalamus, brainstem, and contralateral cerebellar hemisphere. Slight depression of rCBF and rCMRO2 was also observed in the contralateral thalamus and ipsilateral cerebral hemisphere; rOEF was normal in these areas. Though the depression of rCBF and rCMRO2 due to remote effects was detected in all periods, it was mildly observed 0 to 6 days after onset. The reduction of rCBF and rCMRO2 due to remote effects was less than the morphological as well as the functional threshold. The phenomenon is probably caused by neuronal deactivation, and the regions with depressed blood flow and metabolism may be in a "resting" state.

Adult↗

PubMedDate not supplied

Noninvasive assessment of myocardial viability by measuring adenosine triphosphate degradation product in coronary sinus effluent of preserved dog heart.

Isolated dog hearts (n = 19) were preserved in cold Collins solution at 4 degrees C for 1 to 26 hours. At the end of preservation the coronary system was flushed out by cold cardioplegic solution, and the hearts were reperfused with supporting dogs. Myocardial biopsies at the end of preservation and coronary sinus effluents at the time of flush-out were analyzed for adenosine 5'-triphosphate and inosine. Both the degree of depletion in adenosine triphosphate content and the accumulation of inosine in the myocardium during preservation correlated significantly to the preservation time (correlation coefficient = -0.85 and 0.86, respectively). There was a significant correlation between the myocardial inosine level and total amount of inosine released into coronary sinus effluent (correlation coefficient = 0.91, p less than 0.001). Also, a significant correlation between the total amount of inosine in coronary sinus effluent and cellular level of adenosine triphosphate was found (correlation coefficient = -0.86, p less than 0.001). Five hearts that failed to resume beating showed significantly higher amounts of released inosine than the other hearts (3.3 +/- 0.9 versus 1.5 +/- 0.5 mumol, p less than 0.005). These results indicate that the inosine level in the coronary sinus effluent reflects the myocardial energy state, and it is suggested that the measurement of inosine level in the effluent may be applicable as a noninvasive method for assessment of myocardial viability in heart preservation.

Adenosine Triphosphate↗