ABSTRACT
Background: Due to technical difficulties of in vivo observation of blood flow and microvessels in bone, no study has been done concerning the role of blood flow in bone remodeling. Objective: To develop a new window chamber for microscopic observation of the microcirculation in living bone, and to examine the utility of the chamber using rat femur in health and diseases. Methods: A stainless chamber (19 mm in diameter and 5 mm in height) with a circular window (7.5 mm in diameter) for microscopic observation was developed. The chamber was put on rat femur which was exposed for direct observation of the microvasculature. Intravital observation was made of bone blood flow and microvessels, using fluorescence videomicroscopy and confocal laser microscopy. The utility of the chamber was examined based on images of microcirculation (normal and abnormal) in the femur bone. Results and conclusions: Images of rat femur microvasculature were enhanced in the quality by use of the femur window chamber. The new chamber provides a powerful tool for in vivo studies of the bone microcirculation in health and diseases.
ABSTRACT
Background: Many clinical reports have indicated that ascorbic acid (vitamin C) improves vasodilatory impairments in patients with diabetes mellitus, but there is very little in vivo evidence to demonstrate its effectiveness on the brain. Objective: To investigate long-term effects of oral vitamin C administration on the cerebral microvascular vasodilation in diabetes, using streptozotocin (STZ)-induced diabetic rats. Materials and methods: Diabetes was induced in male Wistar Furth rats by a single intravenous injection of STZ (55 mg/kg b.w). Ascorbic acid (vitamin C) was administered in drinking water (1g/l). The rats were divided into control and diabetic groups with or without administration of vitamin C. The cerebral microcirculation was observed at different times (12, 24 and 36 weeks) after vitamin C supplementation, using fluorescence videomicroscopy. Responses of cerebral arterioles to acetylcholine (ACh), adenosine-5 diphosphate (ADP) and nitroglycerine (NTG) were studied by measuring diameters of cerebral arterioles before and after topical application on the cortical surface. Results: The vasodilatory responses of cerebral arterioles to ACh and ADP were significantly decreased in diabetic rats, compared with non-diabetic (control) rats. The response to NTG was not altered in diabetic rats, indicating that the vasodilatory impairment involves at the endothelium. The impaired endothelium-dependent vasodilation was prevented by long-term vitamin C administration. Conclusion: Long-term oral vitamin C administration might be of clinical relevance in improving cerebral microvascular vasodilatory impairment in diabetes.