Effects of electro-acupuncture on endothelium-derived endothelin-1 and endothelial nitric oxide synthase of rats with hypoxia-induced pulmonary hypertension

Abstract

Pulmonary hypertension (PH) is characterized by elevated pulmonary artery pressure (PAP), pulmonary vascular remodeling and right ventricular hypertrophy, which are mainly due to endothelial dysfunction. Electro-acupuncture has shown beneficial effects on cardiovascular homeostasis, but little evidence has been obtained on pulmonary effects. The goal of the present study was to investigate whether electro-acupuncture on bladder-13 and -15 points can protect against chronic hypoxia-induced PH by regulating endothelium-derived endothelin (ET)-1 and endothelial nitric oxide synthase (eNOS). Male Wistar rats were exposed to hypoxia to induce PH. Hemodynamic analysis revealed that mean PAP was similar under normoxic conditions. Chronic hypoxia increased mean PAP to 37 +/- 3 mmHg, and electro-acupuncture attenuated it to 29 +/- 3 mmHg. Absolute right ventricular weight was ameliorated by electro-acupuncture from 0.288 +/- 0.048 g to 0.228 +/- 0.029 g under hypoxic conditions. Hypoxia-induced right ventricular hypertrophy index decreased from 0.477 +/- 0.069 to 0.378 +/- 0.053 with electro-acupuncture treatment. Histological examination revealed that hypoxic rats showed increased medial pulmonary artery wall thickness as well as muscularization. However, these alternations by chronic hypoxia were attenuated by electro-acupuncture. There was no difference in eNOS or ET-1 between groups under normoxic conditions. Electro-acupuncture treatment significantly improved the circulating eNOS concentration (365.36 +/- 31.51 pg/mL) compared with only hypoxia exposure (247.60 +/- 30.64 pg/mL). In lung homogenate, levels of eNOS under hypoxia increased from 684.96 +/- 117.90 to 869.86 +/- 197.61 pg/mg by electro-acupuncture treatment. Levels of ET-1 changed oppositely to eNOS in response to electro-acupuncture (ET-1 in plasma, 29.44 +/- 2.09 versus 20.70 +/- 2.37 pg/mL; ET-1 in lung homogenate, 120.51 +/- 3.03 versus 110.60 +/- 4.04 pg/mg). In conclusion, these results indicated that treatment with electro-acupuncture can protect against hypoxia-induced PH, possibly by regulating the balance of endothelium-derived vasoconstrictors and vasodilators.

Acupuncture Point Specificity

“…A pilot, randomized, double-blind, placebo-controlled crossover trial (Park et al, 2010) showed that flow-mediated dilation was significantly improved with the acupuncture treatment at ST36 and ST36 plus PC6, whereas floor-mediated dilation was unchanged after the acupuncture treatment at PC6 or the sham treatment. Indeed, basic experiments, investigating the mechanisms of acupuncture on regulating endothelial function in rats with hypoxiainduced pulmonary hypertension or with stress-induced hypertention, confirmed that verum acupuncture significantly improved circulation eNOS concentration and markedly increased calcitonin gene-related peptide and nitrogen monoxidum in blood plasma, paralleling to its blood pressure reduction (Pan et al, 2010;Wang, Jing, et al, 2011;Wang, Zhang, et al, 2011).…”

Role of Nrf2/ARE Pathway in Protective Effect of Electroacupuncture against Endotoxic Shock-Induced Acute Lung Injury in Rabbits

“…It was proven that electroacupuncture pretreatment significantly inhibited systemic inflammatory responses and improved survival rate in rats with lethal endotoxemia [6]. Feishu (BL13) acupoint is considered of choice to treat lung diseases and regulate pulmonary functions, Pan et al reported that treatment with electroacupuncture on BL13 showed beneficial effects on hypoxia-induced pulmonary hypertention in rats [7]. Traditionally, acupuncture at Zusanli (ST36) acupoints was known as the modulation of immune functions and is often used in clinical disorders of the immune system [8].…”

Normobaric, intermittent hypoxia conditioning is cardio- and vasoprotective in rats

“…The current 20-d IHC program of brief, normobaric, moderately intense (FIO 2 9.5-10%) hypoxia bouts did not produce right ventricular hypertrophy in Wistar rats. In contrast, normobaric or hypobaric hypoxia programs in which hypoxia exposures of a similar intensity are continuous [68][69][70] or protracted (e.g. 4-8 h bouts) 71,72 provoke right ventricular hypertrophy and medial thickening of the pulmonary vasculature in this strain.…”