Endogenous opioid peptides and mental stress in congestive heart failure patients

Endothelin-1 and psychosocial risk factors for cardiovascular disease: a systematic review

OBJECTIVES

Psychosocial factors (i.e., social environment and emotional factors) contribute to an increased risk of cardiovascular disease (CVD). Perturbation in a potent vasoconstrictive peptide endothelin (ET)-1 could be one of the mechanisms linking psychosocial factors to CVD. Our aim was to evaluate the literature on the relationship between plasma ET-1 and psychosocial risk factors for CVD.

METHODS

MEDLINE and PsycINFO databases were searched for articles on human studies published in peer-reviewed English-language journals through September 2012.

RESULTS

Of the 20 studies that met the inclusion criteria, 14 were experimental studies of acute psychological/mental challenges and 6 were observational studies of psychological and social factors. The inferences drawn from this review were as follows: a) laboratory-induced acute psychological/mental stress may result in exaggerated plasma ET-1 release in those with CVD and those at risk for CVD (positive studies: 5/10); b) chronic/episodic psychosocial factors may have a positive relationship to plasma ET-1 (positive studies: 3/5); and c) race (African American), sex (male), and individual differences in autonomic and hemodynamic responses to stress (parasympathetic withdrawal and elevated blood pressure responsiveness) may moderate the relationship between psychosocial factors and plasma ET-1.

CONCLUSIONS

This review indicates that psychosocial risk factors for CVD are associated with elevated plasma ET-1; however, the relatively small number of studies, methodological differences, and variable assessment tools preclude definitive conclusions about the strength of the association. Specific suggestions regarding the selection of psychosocial factors, optimization of acute challenge protocols, and standardization of methods and timing of the ET-1 measures are provided.

Minimum alveolar concentration of halogenated volatile anaesthetics in left ventricular hypertrophy and congestive heart failure in rats

BACKGROUND

Although many physiological and pathological conditions affect minimal alveolar concentration (MAC), there are no reliable data on the MAC for halogenated anaesthetics during left ventricular hypertrophy (LVH) and congestive heart failure (CHF). The aim of this experimental study was to determine the MAC values of halothane, isoflurane, and sevoflurane in rats, at early and later stages of cardiomyopathic hypertrophy.

METHODS

LVH was induced by ascending aortic stenosis in 3-4-week-old rats. LVH and CHF in each animal were assessed weekly by echocardiography. MAC of halothane, isoflurane, and sevoflurane was determined using the tail-clamp technique in spontaneously breathing rats from each group. Response vs no-response data were analysed using logistic regression analysis. Data are medians (95% confidence interval).

RESULTS

The MAC of halothane [1.30% (1.26-1.34)], isoflurane [1.52% (1.48-1.57)], and sevoflurane [2.93% (2.78-3.07)] in rats with LVH was not different from sham-operated rats [respectively, 1.23% (1.20-1.26), 1.52% (1.47-1.56), and 2.90% (2.79-3.00)]. Conversely, the MAC of halothane [1.44 (1.39-1.50)] and isoflurane [1.74 (1.69-1.78)], but not sevoflurane [2.99 (2.93-3.06)], was significantly increased in rats with CHF.

CONCLUSIONS

MAC values for halothane, isoflurane, and sevoflurane were unchanged in rats with pressure-induced overload LVH. Conversely, the MAC for halothane and isoflurane, but not sevoflurane, was significantly increased in rats with CHF.

Different Effects of Losartan and Moxonidine on Endothelial Function During Sympathetic Activation in Essential Hypertension

The aim of this study was to investigate: 1) the effects of treadmill exercise on plasma catecholamines and endothelin-1 (ET-1, a potent vasoconstrictor) levels in hypertensive patients; and 2) the impact of 1-month therapy with losartan as compared with moxonidine on catecholamine and ET-1 changes during exercise. Twenty-eight patients with essential hypertension were randomized in two groups: group A received losartan and group B received moxonidine for 1 month. Plasma catecholamines exhibited an almost 10-fold increase during exercise (p<0.00001) before treatment. Moxonidine significantly decreased catecholamine levels (p<0.05), while losartan reduction was nonsignificant (p<0.36). Plasma ET-1 increased significantly during exercise before treatment (p<0.00005). Moxonidine therapy did not affect ET-1 levels (p<0.88), while losartan resulted in a significant decrease of ET-1 levels both at baseline and during exercise (p<0.007). These findings suggest a mechanism for the reduced cardiovascular mortality noted with an angiotensin receptor blocker as compared with a sympatholytic agent.

Endothelin-1 response to mental stress in early ischemic lesions of the extremities due to systemic sclerosis

We studied circulating levels of endothelin-1, catecholamines and nitric oxide after a mental arithmetic test in 14 patients with early ischemic lesions of the extremities due to systemic sclerosis and slightly impaired peripheral vascular flow. The test induced an increase (P<0.01) in blood pressure, heart rate, endothelin-1 and catecholamine levels, whereas it did not change the low basal levels of nitric oxide. In healthy subjects (n=20) the test significantly (P<0.01) decreased endothelin-1 without affecting nitric oxide. The low basal levels of nitric oxide and the high plasma concentration of endothelin-1 after psychological stress cannot be explained by an impaired release from the limited ischemic lesions alone. This suggests a diffuse microvascular derangement that aggravates the course of peripheral microvascular ischemic lesions.

Metabolism of dynorphins by peptidases of pulmonary artery endothelial cells

Degradation of several dynorphins by peptidases expressed in cultured porcine pulmonary artery endothelial cells was studied by incubation of the peptide in cell suspensions followed by electrospray ionization and tandem mass spectrometric analyses. Under the in vitro conditions applied, only the metabolism of dynorphin A1-8 occurred in a significant extent. Studies involving specific peptidase inhibitors indicated that mainly bestatin-sensitive aminopeptidases, thiorphan-sensitive endopeptidases, and cFPAAF-pAB-sensitive endopeptidases expressed by the endothelial cells were involved in the process that converted dynorphin A1-8 to dynorphin A2-8, dynorphin A1-6, and leucine enkephalin (dynorphin A1-5), respectively. These peptidases may form a metabolic barrier for the cellular penetration of intact dynorphin A1-8 and/or control effects of the circulating peptide on endothelial opioid receptors of the cells.

Plasma levels of atrial natriuretic peptide in severe burn injury

Atrial natriuretic peptide (ANP) plays a part in the regulation of volume homeostasis and possibly, in the pathophysiology of water and electrolyte disorder. Patients with serious burn injuries risk huge body fluids losses, which are compensated for by perfusion. Blood volume and the renin and aldosterone system are also disturbed. This study measured plasma ANP and vasoactive intestinal polypeptide (VIP) in patients with >20% total burned surface area (TBSA), at admission and 24 h post-admission.Eleven patients (mean age 46.5 years, 8 males) with a mean TBSA of 34.5% were sampled. Standard treatment was given. Eleven closely age-matched volunteers were used as controls. A specific ELISA method suitable for the measurement of ANP and VIP was used.ANP was higher (p<0.0001), while VIP was lower (p=NS) in patients' samples compared to controls. While the level of VIP was higher at 24 h post-admission, mean ANP level remained about the same. The increased levels of plasma ANP may result from volaemic disturbances during resuscitation, low VIP levels, the increase in pulmonary resistance or post-burn stress.

Plasma-circulating levels of natriuretic peptides in patients with bone and soft tissue injuries

To evaluate the release and possible role of N-terminal end of atrial natriuretic factor (ANF) prohormone (proANF-1-30) and C-terminal end of ANF prohormone (aANP-1-28) in patients with soft tissue and bone injuries, 20 patients with soft tissue injuries, 18 bone-fractured patients, and 21 healthy controls were examined. Samples were collected from patients within 24 h after injury. Plasma level of proANF-1-30 and aANP-1-28 were higher in orthopedic patients than the soft tissue injury patients compared to controls (P < 0.005, P<0.05, respectively). proANF-1-30 was over 15-fold greater than aANP-1-28 in the healthy control samples. These data hypothesized that the concentration of proANF-1-30 may be related to tissue damages in man.

Endogenous opiates: 1998

This paper is the twenty-first installment of our annual review of research concerning the opiate system. It summarizes papers published during 1998 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; eating and drinking; alcohol; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurologic disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunologic responses; and other behaviors.

Effects of the angiotensin II antagonist losartan on endothelin-1 and norepinephrine plasma levels during cold pressor test in patients with chronic heart failure

We evaluate the acute hemodynamic and neurohormonal effects of losartan in 15 patients with symptomatic chronic heart failure (CHF), mean age 72+/-8 years, which were classified in two subgroups: (A) Patients with left ventricular ejection fraction (LVEF)< or =0.35 (n = 7); (B) subjects with LVEF>0.35 (n = 8). Sympathetic reactivity (blood pressure, heart rate and plasma norepinephrine) and plasma endothelin-1 (ET-1) were evaluated by a cold pressor test (CPT). Single doses of losartan (50 mg p.o.) lowered delta DBP in both subgroups (A, 8+/-9 to 0+/-5 mm Hg, P<0.05; B, 10+/-6 to 3+/-4 mm Hg, P<0.05) and attenuated the rise of HR in patients with mild (4+/-6 to -1+/-2 bpm, P<0.05) but not with severe (4+/-5 to 2+/-5 bpm, n.s.) impairment of left ventricular function. Losartan blunted the response (delta) of PNE during CPT (A, 142+/-131 to 10+/-74 pg/ml, P<0.05; B, 129+/-72 to 1+/-144 pg/ml, P<0.01). A significant rise in plasma ET-1 was observed during CPT in patients from subgroup B (0.64+/-0.40 to 0.81+/-0.40 fmol/ml, P<0.05) but not in patients with LVEF< or =0.35 (1.79+/-0.44 to 1.51+/-0.66 fmol/ml, n.s.). Losartan attenuated the rise in ET-1 during CPT in patients with LVEF>0.35 (delta ET-1 0.17+/-0.86 to 0.03+/-0.11 fmol/ml, P<0.05), with no significant changes in subgroup A. Acute effects of losartan were characterized by a more favorable hemodynamic and neurohumoral response in patients with chronic heart failure and preserved systolic ventricular function related to subjects with lower ejection fractions.

Opioid peptides in response to mental stress in asymptomatic dilated cardiomyopathy

Fourteen asymptomatic dilated cardiomyopathy patients showing normal plasma levels of beta-endorphin, Met-enkephalin, dynorphin B, norepinephrine and endothelin-1 but elevated atrial natriuretic factor (ANF) levels underwent two Mental Arithmetic Tests (MAT), with placebo and naloxone hydrochloride infusion, respectively. MAT significantly (p < 0.01) increased blood pressure, heart rate, opioid peptides, norepinephrine, ANF, but not endothelin-1. Naloxone infusion significantly (p < 0.05) attenuated the increments produced by MAT in all measured parameters during placebo infusion. These results indicate that in asymptomatic dilated cardiomyopathy the endogenous opioid system, activated by stress-induced sympathoadrenergic hyperactivity, may further increase the sympathetic tone in a positive feedback that is interrupted by naloxone.