Ceramide-induced disruption of endothelial nitric oxide synthase dimerization in bovine aortic endothelial cells (BAECs) is not secondary to peroxynitrite formation

An estimated 23.6 million individuals in the United States have diabetes and of those 90-95% have type II diabetes. Cardiovascular complications (e.g., hypertension and vascular dysfunction) are four-fold more prevalent in patients with type II diabetes.1 The mechanism(s) responsible for increased susceptibility of type II diabetics to cardiovascular complications is unclear. In a previous study, mice that consumed high-fat (HF) vs. standard (CON) chow for 10-14 weeks exhibited: systemic disturbances characteristic of the metabolic syndrome; vascular dysfunction; and hypertension.2 Because free fatty acids (FFAs) were elevated three-fold in those HF mice, we investigated whether the fat derived metabolite ceramide might contribute to cardiovascular complications. To do so, mice consumed HF chow and were treated concurrently with the ceramide biosynthesis inhibitor myriocin or vehicle. Cardiovascular (e.g., hypertension and vascular dysfunction) and metabolic (e.g., impaired glucose tolerance and dyslipidemia) complications did not develop in myriocin vs. vehicle-treated HF mice.3 Importantly, subsequent in vitro experiments using pharmacological and genetic approaches to inhibit ceramide biosynthesis showed this sphingolipid impairs endothelium-dependent function in a tissue autonomous manner.4 To gain insight into mechanisms responsible for ceramide-induced endothelial dysfunction, BAECs were incubated with palmitate to precipitate endogenous ceramide biosynthesis. Results are shown in Fig. 1 - Panels A-C.