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Nitric Oxide is Necessary for Diazoxide Protection Against Ischemic Injury in Skeletal Muscle
Hossein Farahini1, Marjan Ajami, Jalaledin Mirzay Razaz
1Department of Orthopedic Surgery, Tehran University of Medical Sciences, Tehran, Iran.
Abstract:
Ischemia reperfusion injury (IR injury) is a common problem in clinical conditions. Researches have frequently revealed that ATP- sensitive potassium (KATP) channels and nitric oxide plays a role in protection against ischemic injury in skeletal muscle. The present study aimed at evaluating the possible link between this two pathways. Sixty-eight male wistar rats, were pretreated with saline, diazoxide (KATP opener; 45 mg/Kg, IP), glibenclamide (KATP inhibitor; 5 mg/Kg), or L-NAME (iNOS inhibitor; 20 mg/Kg, IP) before 3 h ischemia and 2 h reperfusion. Activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and the level of malondialdehyde (MDA) and expression of iNOS were measured in muscle tissue. Tissue MDA content was significantly increased by IR (p < 0.001). Diazoxide significantly decreased the IR-induced elevation of tissue MDA level (p < 0.05) and Glibenclamide increased MDA (p < 0.05 vs. IR group). L-NAME inhibited the effect of diazoxide on decreasing MDA (p < 0.01 vs., diazoxide+IR group) and IR decreased the activity of SOD and CAT (p < 0.01), while pretreatment with diazoxide increased activity of SOD and CAT (p < 0.01). Glibenclamide decreased SOD and CAT activity after IR (p < 0.05). L-NAME pretreatment in diazoxide-treated rats abolished the effect of diazoxide on increasing the activity of SOD and CAT (p < 0.05 vs. Diaz+IR). Expression of iNOS was increased by IR (p < 0.01 vs. Sham group). Diazoxide significantly decreased iNOS expression after IR (p < 0.05 vs. IR). L-NAME significantly decreased iNOS expression after IR (p < 0.01) in diazoxide-treated rats (p < 0.01 vs. Diaz+IR). In conclusion, the results of present study suggested a NO dependent protective effect for diazoxide against muscle IR injury.
Insights
Diazoxide, a potassium channel opener, protects skeletal muscle from ischemia reperfusion injury by increasing antioxidant enzymes and reducing oxidative stress. This protective effect is dependent on nitric oxide signaling.
Area of Science:
- Biomedical Sciences
- Physiology
- Pharmacology
Background:
- Ischemia reperfusion (IR) injury is a significant clinical challenge, particularly in skeletal muscle.
- ATP-sensitive potassium (KATP) channels and nitric oxide (NO) are implicated in mitigating IR injury.
- The interplay between KATP channels and NO pathways in skeletal muscle IR injury requires further elucidation.
Purpose of the Study:
- To investigate the potential link between KATP channels and nitric oxide pathways in protecting skeletal muscle against IR injury.
- To evaluate the effects of KATP channel modulation and nitric oxide inhibition on biochemical markers of oxidative stress and antioxidant enzyme activity.
Main Methods:
- Sixty-eight male Wistar rats were subjected to 3 hours of ischemia followed by 2 hours of reperfusion.
- Pretreatments included saline, diazoxide (KATP opener), glibenclamide (KATP inhibitor), or L-NAME (iNOS inhibitor).
- Muscle tissue was analyzed for malondialdehyde (MDA) levels, superoxide dismutase (SOD) and catalase (CAT) activities, and inducible nitric oxide synthase (iNOS) expression.
Main Results:
- IR significantly increased MDA levels and decreased SOD and CAT activities, indicating oxidative stress and reduced antioxidant capacity.
- Diazoxide pretreatment attenuated MDA elevation and restored SOD and CAT activities, while glibenclamide exacerbated MDA levels and reduced enzyme activities.
- IR increased iNOS expression; diazoxide decreased it, an effect abolished by L-NAME, suggesting a NO-dependent mechanism.
Conclusions:
- Diazoxide demonstrates a protective effect against skeletal muscle IR injury, evidenced by reduced oxidative stress and enhanced antioxidant enzyme function.
- The protective role of diazoxide appears to be mediated through a nitric oxide-dependent pathway.
- These findings suggest that targeting KATP channels could be a therapeutic strategy for managing IR injury in skeletal muscle.
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