Nitric Oxide Synthase Isoforms I, III and Protein Kinase-Cθ in Skeletal Muscle Fibres of Normal and Streptozotocin-induced Diabetic Rats With and Without Ginkgo Biloba Extract Treatment

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Abstract
The expression of nitric oxide synthase (NOS) isoforms I, III and protein kinase-Cθ (PKCθ) in rat vastus lateralis muscle was demonstrated immunohistochemically and then correlated to the physiological metabolic fibre types: SO (slow-oxidative), FOGI, FOGII (fast-oxidative glycolytic; I more glycolytic, II more oxidative), and FG (fast-glycolytic). NOS expression in muscles from different experimental groups (normal and diabetic rats, with and without Ginkgo biloba extract treatment) was assayed by Western blotting. Generally, NOS I and PKCθ were co-expressed in fibres with predominantly oxidative metabolism (SO, FOGII). This suggests an interplay of PKCθ and NOS I in nitric oxide production by oxidative fibres. NOS III was more highly expressed in fibres with predominantly glycolytic metabolism (FOGI, FG). A somewhat lower NOS I immunoreactivity was also found in NOS III positive fibres suggesting that NOS III and NOS I are co-expressed in these fibres. Western blotting revealed that NOS I as well as NOS III expression in the vastus lateralis muscle was down-regulated in diabetes and increased after Ginkgo biloba extract treatment. These effects may be associated with a diminished glucose uptake by myocytes of diabetic muscles and with an improved muscle function after Ginkgo biloba treatment.