Key result
Low-flow ischaemia rapidly and persistently stimulated cytosolic nitric oxide synthase activity in isolated perfused rabbit hearts.
Ischaemia rapidly and persistently stimulates cytosolic nitric oxide synthase activity in the isolated perfused rabbit heart.
Should not alter clinical practice; leaves open cytosolic NOS role in human myocardial ischemia.
OBJECTIVE: Recent data have indicated that the activity of nitric oxide synthase (NO synthase), the enzyme producing NO from L-arginine, could be modified by ischaemia. The aim of the present work was therefore to study whether ischaemia activated NO synthase. METHODS: NO synthase activity was measured by the conversion of radioactive arginine into citrulline in extracts of isolated perfused rabbit hearts submitted to low-flow ischaemia and reperfusion. RESULTS: When measured in heart homogenates, NO synthase activity was significantly increased during ischaemia. This activation was already detectable after 5 min of ischaemia and was maintained during the whole ischaemic period. After cell fractionation, NO synthase was recovered in cytosolic and membrane fractions. The increase in NO synthase activity by ischaemia was related to an activation of the cytosolic activity, while the membrane-bound NO synthase activity remained constant. CONCLUSION: NO synthase activity in the heart is rapidly stimulated by ischaemia and this stimulation is maintained during the whole ischaemic episode. This activation is found only in the cytosolic fraction, whereas the particulate activity is not affected by ischaemia.
No takes yet. Share an insight, caveat, or question.
C. Depre (1997) studied Ischaemia. Low-flow ischaemia was evaluated on Nitric oxide synthase (NO synthase) activity. Low-flow ischaemia rapidly and persistently stimulated cytosolic nitric oxide synthase activity in isolated perfused rabbit hearts.