Endothelin receptor blockade blunts the pressor response to acute stress in men and women with obesity

Altered Autonomic Function in Metabolic Syndrome: Interactive Effects of Multiple Components

Metabolic syndrome (MetS) describes a set of disorders that collectively influence cardiovascular health, and includes hypertension, obesity, insulin resistance, diabetes, and dyslipidemia. All these components (hypertension, obesity, dyslipidemia, and prediabetes/diabetes) have been shown to modify autonomic function. The major autonomic dysfunction that has been documented with each of these components is in the control of sympathetic outflow to the heart and periphery at rest and during exercise through modulation of the arterial baroreflex and the muscle metaboreflex. Many studies have described MetS components in singularity or in combination with the other major components of metabolic syndrome. However, many studies lack the capability to study all the factors of metabolic syndrome in one model or have not focused on studying the effects of how each component as it arises influences overall autonomic function. The goal of this review is to describe the current understanding of major aspects of metabolic syndrome that most likely contribute to the consequent/associated autonomic alterations during exercise and discuss their effects, as well as bring light to alternative mechanisms of study.

Endothelin-1 receptor blockade does not alter the sympathetic and hemodynamic response to acute intermittent hypoxia in men

Repeat exposures to low oxygen (intermittent hypoxia, IH), like that observed in sleep apnea, elicit increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in men. Endothelin (ET) receptor antagonists can attenuate the sympathetic and BP response to IH in rodents; whether these data translate to humans are unclear. We hypothesized that ET-receptor antagonism would ameliorate any rise in MSNA and BP following acute IH in humans. Twelve healthy men (31 ± 1 yr) completed two visits (control, bosentan) separated by at least 1 wk. MSNA, BP, and baroreflex sensitivity (modified Oxford) were assessed during normoxic rest before and following 30 min of IH. The midpoint (T50) for each individual's baroreflex curve was calculated. Acute IH increased plasma ET-1 (P < 0.01), MSNA burst frequency (P = 0.03), and mean BP (P < 0.01). There was no effect of IH on baroreflex sensitivity (P = 0.46), although an increase in T50 was observed (P < 0.01). MSNA burst frequency was higher (P = 0.04) and mean BP (P < 0.01) was lower following bosentan treatment compared with control. There was no effect of bosentan on baroreflex sensitivity (P = 0.53), although a lower T50 was observed on the bosentan visit (P < 0.01). There was no effect of bosentan on increases in MSNA (P = 0.81) or mean BP (P = 0.12) following acute IH. Acute IH results in an increase in ET-1, MSNA, and BP in healthy young men. The effect of IH on MSNA and BP is not attenuated following ET-receptor inhibition. Present data suggest that acute IH does not increase MSNA or BP through activation of ET-receptors in healthy young men.NEW & NOTEWORTHY Repeat exposures to low oxygen (intermittent hypoxia, IH) elicit increases in muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in men. Endothelin (ET) receptor antagonists can attenuate the sympathetic and BP response to IH in rodents; whether these data translate to humans were unclear. We show acute IH results in an increase in ET-1, MSNA, and BP in healthy young men; however, the effect of IH on MSNA and BP does not occur through activation of ET-receptors in healthy young men.

Endothelin-1 as a novel target for the prevention of metabolic dysfunction with intermittent hypoxia in male participants

We examined the effect of intermittent hypoxia (IH, a hallmark feature of sleep apnea) on adipose tissue lipolysis and the role of endothelin-1 (ET-1) in this response. We hypothesized that IH can increase ET-1 secretion and plasma free fatty acid (FFA) concentrations. We further hypothesized that inhibition of ET-1 receptor activation with bosentan could prevent any IH-mediated increase in FFA. To test this hypothesis, 16 healthy male participants (32 ± 5 yr, 26 ± 2 kg/m2) were exposed to 30 min of IH in the absence (control) and presence of bosentan (62.5 mg oral twice daily for 3 days prior). Arterial blood samples for ET-1, epinephrine, and FFA concentrations, as well as abdominal subcutaneous adipose tissue biopsies (to assess transcription of cellular receptors/proteins involved in lipolysis), were collected. Additional proof-of-concept studies were conducted in vitro using primary differentiated human white preadipocytes (HWPs). We show that IH increased circulating ET-1, epinephrine, and FFA (P < 0.05). Bosentan treatment reduced plasma epinephrine concentrations and blunted IH-mediated increases in FFA (P < 0.01). In adipose tissue, bosentan had no effect on cellular receptors and proteins involved in lipolysis (P > 0.05). ET-1 treatment did not directly induce lipolysis in differentiated HWP. In conclusion, IH increases plasma ET-1 and FFA concentrations. Inhibition of ET-1 receptors with bosentan attenuates the FFA increase in response to IH. Based on a lack of a direct effect of ET-1 in HWP, we speculate the effect of bosentan on circulating FFA in vivo may be secondary to its ability to reduce sympathoadrenal tone.

[Effect of somatostatin on postoperative gastrointestinal function and stress level in children with acute abdomen: a prospective randomized controlled study]

OBJECTIVES

To study the effect of somatostatin on postoperative gastrointestinal function and stress level in children with acute abdomen.

METHODS

A total of 102 children with acute abdomen who underwent surgery in Xuzhou Children's Hospital from August 2019 to June 2021 were enrolled as subjects and were randomly divided into an observation group and a control group, with 51 children in each group. The children in the control group were given conventional treatment such as hemostasis and anti-infective therapy after surgery, and those in the observation group were given somatostatin in addition to conventional treatment. Peripheral blood samples were collected from both groups before surgery and on days 1 and 5 after surgery. The two groups were compared in terms of the serum levels of endothelin-1 (ET-1), adrenocorticotropic hormone (ACTH), cortisol, gastrin, and motilin, postoperative recovery, and the incidence rate of complications.

RESULTS

There was no significant difference in the serum levels of ET-1, ACTH, cortisol, gastrin, and motilin between the two groups before surgery (P>0.05). Compared with the control group, the observation group had significantly lower serum levels of ET-1, ACTH, and cortisol on days 1 and 5 after surgery (P<0.05) and significantly higher levels of motilin and gastrin on day 5 after surgery (P<0.05). Compared with the control group, the observation group had significantly shorter time to first passage of flatus, first bowel sounds, and first defecation after surgery, as well as a significantly shorter length of hospital stay (P<0.05). The incidence rate of complications in the observation group was significantly lower than that in the control group (6% vs 24%, P<0.05).

CONCLUSIONS

In children with acute abdomen, somatostatin can significantly reduce postoperative stress response, improve gastrointestinal function, and reduce the incidence rate of complications, thereby helping to achieve a good prognosis.

Endothelin-1 response to whole-body vibration in obese and normal weight individuals

Upregulation of endothelin-1 (ET-1) is the hallmark of various cardiovascular diseases (CVD). The purpose of the present study was to assess the ET-1 response to an acute bout of whole-body vibration (WBV) in humans and to determine the role of adiposity. Twenty-two participants volunteered for the study; they were grouped into overweight/obese [(OW/OB): n = 11, Age: 33 ± 4 years, Body mass index (BMI): 35 ± 10 kg/m² ] or normal weight [(NW): n = 11, Age: 28 ± 7 years, BMI: 21 ± 2 kg/m² ]. Participants engaged in 10 cycles of WBV exercise (1 cycle = 1 min WBV followed by 30 s of rest). Blood samples were analyzed for ET-1 pre-WBV (PRE), immediately post (POST), 1 h (1H), 3 h (3H), and 24 h (24H) post-WBV. There was a significant time main effect of WBV on circulating ET-1 (F = 12.5, p < 0.001); however, the ET-1 response was similar (F = 0.180, p = 0.677) between groups. Specifically, compared to PRE, a significant increase in ET-1 was observed at 1H (p = 0.017) and 3H (p = 0.025). In addition, concentrations of ET-1 were significantly lower at 24H compared to PRE (p = 0.019), 1H (p < 0.001), and 3H (p < 0.001). Maximal oxygen uptake during WBV was similar between the two groups. Acute WBV resulted in an initial rise in ET-1, followed by a significantly lower ET-1 at 24H in both groups. Findings support the utility of routine WBV exercise to elicit a decrease in ET-1 and improve CVD risk, similar to what has been reported with traditional modes of exercise.