A case of sleep apnea syndrome manifesting severe hypertension with high plasma norepinephrine levels

Clinical utility of urinary levels of catecholamines and their fraction ratios related to heart rate and thyroid function

Urinary catecholamines (CAs) have been examined for the screening of pheochromocytomas. The decision to perform screening is based on symptoms suggesting secondary hypertension or hyperactivities of the sympathetic nervous system. To elucidate the usefulness of urinary fractions and ratios of CAs, 79 patients in whom 24-h excretions of urinary CAs including adrenaline (AD), noradrenaline (NA) and dopamine (DA) had been examined from 2015 until 2020 were retrospectively analyzed. There were no significant differences in urinary CA levels between two age groups, gender groups and two BMI groups. Patients with histories of preexisting hypertension and diabetes showed significantly higher levels of urinary NA excretion, and the urinary ratio of NA/DA was also increased in the patients with a history of hypertension. Heart rate (HR) was significantly correlated with the urinary ratio of NA/DA. Serum free thyroxine (FT4) concentration and ratio of FT4/thyrotropin (TSH) were correlated with the level of urinary AD. The levels of TSH and FT4/TSH showed negative and positive correlations, respectively, with the urinary NA/DA ratio. Thus, increases of HR are related to the enhanced conversion of DA to NA and increased thyroid hormones are involved in the increase in urinary AD and the conversion of DA to NA. History of lifestyle-related diseases and changes of HR and thyroid functions need to be considered for the evaluation of urinary CAs and their ratios.

Fast determination of 16 circulating neurotransmitters and their metabolites in plasma samples of spontaneously hypertensive rats intervened with five different Uncaria

This study aimed to establish a sensitive, reproducible, and rapid liquid chromatography method with tandem mass spectrometry detection to perform simultaneous quantitative analysis of 16 neurotransmitters and their metabolites in rat plasma, including levodopa, dopamine, norepinephrine, epinephrine, L-tryptophan, kynurenic acid, serotonin, melatonin, choline, acetylcholine, histamine, phenylethylamine, as well as excitatory (L-glutamic acid and L-aspartic acid) and inhibitory (γ-aminobutyric acid and L-glycine) neurotransmitters. These analytes were measured by ultra-high performance chromatography coupled with triple quadrupole mass spectrometry using a hydrophilic interaction chromatographic column (ethylene-bridged hybrid amide column). The internal standards of stable isotope labeling were used to improve the reliability of the results. Our method provided high linearity for all neurotransmitters (for all coefficients measured > 0.99), with inter- and intra-day accuracy from -14.82% to 17.49% and precision was between 0.89% and 17.70%. The method was subsequently verified in an animal study, where the intervention of five different Uncarias, the traditional Chinese medicine with hypotensive effects, was applied to the spontaneously hypertensive rats (SHRs). SHRs showed dysregulated plasma kynurenic acid, acetylcholine, and norepinephrine levels, and these neuroactive analytes were significantly restored by Uncaria treatment compared with the model group (SHR group). Compared with captopril, included as a positive control for its hypotensive effect, Uncaria had more effects on perturbing the levels of plasma neurotransmitters, which might indicate Uncaria's potential in treating symptoms related to the nervous system. These results suggested that the changes in the neurotransmitters and their metabolites in plasma may be related to the pathogenesis of hypertension. It also provided valuable information about the action mechanisms of Uncaria on its hypotensive effects.

Continuous positive airway pressure therapy reduces the levels of catecholamines and blood pressure in pseudophaeochromocytoma with coexisting obstructive sleep apnoea

Background

Stress from obstructive sleep apnoea (OSA) stimulates catecholamine release and consequently can exacerbate hypertension, even in the absence of a catecholamine-producing tumour (phaeochromocytoma). As such, a positive screening test for suspected phaeochromocytoma may be misleading. There exists only a handful case reports, and no controlled trials, how continuous positive airway pressure (CPAP) to treat OSA influences catecholamine levels. We examined changes to levels of urinary catecholamine and blood pressure in response to CPAP treatment.

Methods

We conducted a meta-analysis of data aggregated from published case reports of individual patient data up to April 2020. The quality of the reports was evaluated using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool.

Results

A total of 13 cases (seven men and six women) from seven reports met our search criteria. Patients had mean age of 49.1 years (range = 36-62) and body mass index of 37.4 kg/m² (range = 27-56). Most had moderate to severe OSA with CPAP treatment. Nine cases had 24-hour urinary noradrenaline assessment before and after CPAP treatment. CPAP treatment led to a 21% reduction (104 nmol/24-hours, 95% credible interval =59 to 148) in 24-hour urinary noradrenaline to within reference ranges, and 25% reduction (from 131 to 100 mmHg) in mean arterial pressure. The risk of overall bias evaluated by the ROBINS-I tool was found to be low in the majority of reports.

Conclusions

Investigations of patients suspected of phaeochromocytoma, particularly obese individuals, should exclude OSA and treat this condition if present before performing screening tests to assess for catecholamine levels.

Aircraft noise exposure affects rat behavior, plasma norepinephrine levels, and cell morphology of the temporal lobe

In order to investigate the physiological effects of airport noise exposure on organisms, in this study, we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 d. For comparison, we also used unexposed control rats. Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels (L(WECPN)) of 75 and 80 dB for the two experimental groups. We examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD). We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM). Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number (P<0.05) and significantly longer center area duration (P<0.05) than control animals. After 29 d of airport noise exposure, the concentration of plasma NE of exposed rats was significantly higher than that of the control group (P<0.05). We also determined that the neuron and synapsis of the temporal lobe of rats showed signs of damage after aircraft noise of 80 dB exposure for 65 d. In conclusion, exposing rats to long-term aircraft noise affects their behaviors, plasma NE levels, and cell morphology of the temporal lobe.

Gastric diverticulum simulating left adrenal incidentaloma in a hypertensive patient

A 46-year-old Japanese male with hypertension was referred for examination of left adrenal tumor incidentally detected by computed tomography (CT) scan. The patient had a 4-month history of hypertension. Abdominal CT demonstrated a low-density mass 2.5 cm in diameter in the left adrenal region that was observed as a high-intense lesion with T2-weighted magnetic resonance imaging. (131) I-adosterol scintigraphy showed normal uptake of bilateral adrenals. The adrenocortical hormone levels were within normal ranges; however, urinary noradrenaline excretion was slightly elevated, likely due to concurrent sleep apnea syndrome. Based on the observation of a very tiny bubble in the ventral portion of the adrenal mass by careful review of CT images examined at a previous hospital, a restudy of abdominal CT with oral contrast was performed. In this restudy abdominal CT we observed positive enhancement of the left adrenal mass, indicating that the adrenal mass was a diverticulum derived from posterior gastric fornix. The present case study reinforces that preoperative differentiation from mimic adrenal tumors is necessary in cases of cystic adrenal mass in the left adrenal region.