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Dexamethasone increases survival and attenuates induction of inducible nitric oxide synthase in experimental skin
O Gribbe1, T Lundeberg, U E Samuelson
1Department of Physiology and Pharmacology, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
Abstract:
The molecule nitric oxide synthesized by the enzyme nitric oxide synthase (NOS) has been shown to be of major physiological and pathophysiological importance in the body. During ischemia and reperfusion, induction of free ionic calcium (Ca2+)-independent inducible NOS (iNOS) is thought to result in an overproduction of NO, leading to tissue damage. The glucocorticoid dexamethasone is known to inhibit the induction of iNOS, and the aim of the current study was to determine the effect of dexamethasone on viability and NOS activity in an ischemic flap model on the dorsum of the rat. Vehicle (N = 20) or dexamethasone (N = 20) was administered 3 hours prior to operation. The surviving area was measured and the flaps were removed after 24 hours for 10 rats in each group and after 48 hours for the remaining 10 rats in each group. Treatment with dexamethasone resulted in an improved flap viability at both 24 hours (p < 0.001) and 48 hours (p < 0.01), and a reduced induction of Ca2+-independent NOS activity in the proximal part of the flaps at 24 hours (p < 0.001). In the current study the authors show that dexamethasone attenuates the induction of Ca2+-independent NOS and increases survival in experimental skin flaps.
Insights
Dexamethasone improves survival in experimental skin flaps by reducing inducible nitric oxide synthase (iNOS) activity. This study demonstrates the therapeutic potential of dexamethasone in mitigating tissue damage during ischemia and reperfusion.
Area of Science:
- Biomedical Science
- Pharmacology
- Surgical Research
Background:
- Nitric oxide (NO), synthesized by nitric oxide synthase (NOS), plays critical roles in physiology and pathophysiology.
- Inducible NOS (iNOS) overproduction of NO during ischemia-reperfusion contributes to tissue damage.
- Glucocorticoids like dexamethasone are known to inhibit iNOS induction.
Purpose of the Study:
- To investigate the effects of dexamethasone on flap viability and NOS activity in a rat ischemic flap model.
- To determine if dexamethasone can attenuate the induction of calcium (Ca2+)-independent iNOS.
Main Methods:
- A rat dorsal ischemic flap model was utilized.
- Rats received either vehicle or dexamethasone 3 hours before surgery (N=20 per group).
- Flap viability was assessed at 24 and 48 hours; NOS activity was measured in proximal flap sections.
Main Results:
- Dexamethasone significantly improved flap viability at both 24 hours (p < 0.001) and 48 hours (p < 0.01).
- Treatment with dexamethasone reduced the induction of Ca2+-independent NOS activity at 24 hours (p < 0.001).
Conclusions:
- Dexamethasone treatment enhances survival in experimental skin flaps.
- Dexamethasone effectively attenuates the induction of Ca2+-independent NOS, suggesting a protective mechanism against ischemia-reperfusion injury.