Changes in Nitric Oxide, cGMP, and Nitrotyrosine Concentrations Over Skin Along the Meridians in Obese Subjects

Abstract

The purposes of these studies were to quantify the concentrations of total nitrate and nitrite (NOx−) cyclic guanosine monophosphate (cGMP), and nitrotyrosine over skin surface in normal weight healthy volunteers (n = 64) compared to overweight/obese subjects (n = 54). A semicircular plastic tube was taped to the skin along acupuncture points (acupoints), meridian line without acupoint (MWOP), and nonmeridian control and filled with a 2-Phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl solution for 20 min. The concentrations of NOx−, cGMP, and nitrotyrosine in the samples were quantified in a blinded fashion using chemiluminescence and enzyme-linked immunosorbent assay, respectively. In normal weight healthy volunteers, NOx− and cGMP concentrations were consistently increased over the pericardium meridian (PC) 4–7 compared with nonmeridian areas. NOx− concentration is enhanced over the bladder meridian (BL) 56–57, but cGMP level is similar between the regions. In overweight/obese subjects, NOx− contents were increased or tended to be elevated over PC and BL regions. cGMP is paradoxically decreased over PC acupoints and nonmeridian control on the forearm but the decreases were blunted along BL regions on the leg. Nitrotyrosine concentrations are markedly elevated (five- to sixfold) over both PC and BL in all areas of overweight/obese subjects. This is the first evidence showing that nitrotyrosine level is tremendously elevated over skin accompanied by paradoxical changes in nitric oxide (NO)-cGMP concentrations over PC skin region in overweight/obese subject. The results suggest that NO-related oxidant inflammation is systemically enhanced while cGMP generation is impaired over PC skin region but not over BL region in obesity.

Nitric oxide signaling molecules in acupoints: Toward mechanisms of acupuncture

“…(37) The investigation of NO bioavailability over the skin surface is confirmed by other studies, (38) and is a potential physiological indicator for therapeutic manipulation of the skin microvasculature and in pathophysiology. (23,29,34) These results suggest that NO is physiologically released/generated from the skin surface with a high level at acupoints.…”

“…Our studies demonstrated, using this biocapture device, that concentrations of NOx - and cGMP can be captured over the forearm along the Pericardium Meridian (PC) and the leg along the Bladder Meridian regions by using this device in humans. (33,34) NOx - and cGMP levels are consistently increased over skin acupoints compared to non-meridian control regions. The results are consistent with data from dermal microdialysis in healthy humans reporting that NO-cGMP releases in the subcutaneous tissue of acupoint are higher than those in NMCR and increased by acupuncture stimulation.…”

“…Then, aqueous PTIO solution will be placed inside the tubing contacting the surface of the skin for 20 min in order to absorb NO. (33,34) The liquid was drained from the tube. Concentrations of NOx - (total nitrite and nitrate, the stable metabolites of NO), and nitrotyrosine and cGMP in the samples were quantified by using chemiluminescence and an enzyme-linked immunoSorbent assay in a blinded fashion, respectively.…”

Are Oxygen and Related Compounds the Mechanisms Underlying Acupoint Function? A Review of Acupoint Oxygen Specificity Studies

“…Liu et al [31] developed and used an NO sensor in experiments on meridians in rats and showed that there were differences between acupoints and corresponding non-acupoints in terms of NO content, demonstrating the specificity of acupoints. However, Ma et al [32] at the University of California suggested that NO needle sensor insertion into the skin is painful, which may have side effects or may cause infection. They therefore used the NO scavenger PTIO in a plastic pipe that attaches to the skin for 20 min to collect NO released from acupoints [32].…”

“…However, Ma et al [32] at the University of California suggested that NO needle sensor insertion into the skin is painful, which may have side effects or may cause infection. They therefore used the NO scavenger PTIO in a plastic pipe that attaches to the skin for 20 min to collect NO released from acupoints [32]. Although this method can precisely test the emission of NO from the skin, the test pipe is large and can only be placed on the skin surface while the deep NO content at the acupoints cannot be tested.…”