Search PubMed⌕ Search

Biomedical subjects

K Kumamoto

Publications and source records attributed to K Kumamoto.

66 records · Page 4Linked to original sources
PubMed1978

Brain metabolism and arterial acid-base balance following bilateral carotid occlusion in normotensive and experimental hypertensive rats.

The effects of bilateral common carotid artery occlusion on brain metabolism and arterial acid-base balance were studied in normotensive and experimental renovascular hypertensive rats. One hour after carotid occlusion in hypertensive rats, supratentorial lactate increased to 383% and lactate-pyruvate ratio to 280% of the controls, while adenosine triphosphate (ATP) decreased to 69%. These metabolic changes were thought to be due to cerebral ischemia. Arterial pCO2 was lowered and the pH was raised in the hypertensive animals due to cerebral ischemia induced hyperventilation. In the normotensive rats, carotid occlusion had minimal effects on cerebral metabolism and arterial acid-base balance. These results suggest that hypertensive rats are more susceptible to cerebral ischemia caused by carotid occlusion than normotensive rats. Increased cerebrovascular resistance in hypertension is discussed as a causal factor in cerebral ischemia.

Acid-Base Equilibrium↗
PubMed1977

Plasma dopamine-beta-hydroxylase activity in normal young men: its responsiveness to manipulation of sodium balance and upright posture.

Plasma dopamine-beta-hydroxylase (DBH) activity was examined in nine healthy young adults. DBH activity at rest had a wide range, near 0 to 44 I.U./L. When sodium depletion was performed by dietary sodium restriction and diuretic, the activity was significantly increased. With dietary sodium loading, it was decreased. The change in DBH activity was significantly correlated with that in hematocrit. When subjects were erected, the enzyme activity was elevated in situations regardless of sodium balance. Blood pressure and pulse rate were changed by manipulation of sodium balance and postural change. However, the change in DBH activity did not correlate with them. Plasma renin activity (PRA) was determined concomitantly in the same plasma with DBH. The change in PRA had a direct correlation with that in DBH activity. Furthermore, the change in mean arterial pressure induced by infusion of angiotensin II analogue seemed to correlate with DBH activity change by sodium depletion. When the values of DBH activity in each individual were compared throughout the study, it was observed that the biggest variance in the activity of each individual was significantly correlated with the basal activity. In longitudinal study of individuals, plasma DBH activity could be a useful index for estimation of sympathetic activity.

Adult↗
PubMedDate not supplied

Brain metabolism following bilateral carotid occlusion in 2 different models of experimental hypertensive rats.

Brain metabolites and arterial acid-base measurements were made one hr after bilateral carotid artery occlusion in 2 different models of hypertensive rats. Animals used included renovascular hypertensive rats (RHR) with an altered renin-angiotensin system and desoxycorticosterone hypertensive rats (DHR) with low plasma renin activity (PRA). The mean value for supratentorial lactate of 7.41 mM/kg in RHR was significantly higher than in DHR (3.90 MM/kg) or in control normotensive rats (3.10 - 2.56 mM/kg). Concomitantly, the lactate/pyruvate ratio tended to increase and ATP to decrease in RHR only. In these same rats (RHR) infratentorial lactate was also increased. The results suggest that bilateral carotid occlusion leads to anaerobic metabolism of the brain in RHR but not in DHR, suggesting that the renin-angiotensin system may play some role in the susceptibility to cerebral ischemia following carotid occlusion in the hypertensive rats.

Adenosine Triphosphate↗