Nitric oxide synthase isoforms I, III and protein kinase-C theta in skeletal muscle fibres of normal and streptozotocin-induced diabetic rats with and without Ginkgo biloba extract treatment

The expression of nitric oxide synthase (NOS) isoforms I, III and protein k inase-C theta (PKC theta) in rat vastus lateralis muscle was demonstrated i mmunohistochemically and then correlated to the physiological metabolic fib re types: SO (slow-oxidative), FOGI, FOGII (fast-oxidative glycolytic; I mo re glycolytic, II more oxidative), and FG (fast-glycolytic). NOS expression in muscles from different experimental groups (normal and diabetic rats, w ith and without Ginkgo biloba extract treatment) was assayed by Western blo tting. Generally, NOS I and PKC theta were co-expressed in fibres with pred ominantly oxidative metabolism (SO, FOGII). This suggests an interplay of P KC theta and NOS I in nitric oxide production by oxidative fibres. NOS III was more highly expressed in fibres with predominantly glycolytic metabolis m (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 expre ssion in the vastus lateralis muscle was down-regulated in diabetes and inc reased after Ginkgo biloba extract treatment. These effects may be associat ed with a diminished glucose uptake by myocytes of diabetic muscles and wit h an improved muscle function after Ginkgo biloba treatment.