Abnormally increased nitric oxide synthesis and increased endothelin-1 in plasma in patients with obstructive sleep apnoea

What Was Tested

This randomized controlled trial paper looks at Endothelin-1.

Obstructive sleep apnoea (OSA) is a risk factor for cardiovascular morbidity and mortality.

The mechanism is unknown, but endothelial dysfunction might contribute.

The researchers tested the hypothesis that patients with OSA have abnormal nitric oxide (NO) synthesis, which results in an abnormal response in blood pressure, renal hemodynamics, renal tubular function and vasoactive hormones in response to inhibition of the NO synthesis with L-NMMA.

Who Took Part

The abstract describes 13 patients taking part.

The age groups tagged for this paper are adults, middle-aged adults and older adults, both men and women.

A randomized, placebo-controlled, single-blinded, crossover study was done in 13 OSA patients and 14 controls.

How the Study Was Run

In design terms this was a randomized, single-blind, placebo-controlled and crossover study.

Because people in this Endothelin-1 study were split into groups at random, differences between the groups are less likely to reflect who happened to join each one.

In this single-blind Endothelin-1 study one party knew the assignments and the other did not.

The comparison arm used a placebo, so changes seen with Endothelin-1 could be set against what happens without it.

Each person switched between Endothelin-1 and the comparison at some point, usually with a gap in between.

The researchers measured changes in systolic and diastolic blood pressure (SBP and DBP), pulse rate, glomerular filtration rate, renal plasma flow, fractional excretion of sodium and lithium and plasma concentrations of vasoactive hormones after injection of L-NMMA and placebo.

What Was Measured

The subject headings attached to it are Blood Pressure, Endothelin-1, Heart Rate, NG-Nitroarginine Methyl Ester, Nitric Oxide, Renal Circulation and Sleep Apnea, Obstructive.

What This Means in Plain Language

The paper is a randomized, single-blind and placebo-controlled study of Endothelin-1 in 13 patients.

With fewer than 40 people, it is a small study, so it is better read as an early signal for further research than as a settled answer.

Results are reported in around 7 sentences of the abstract; we leave them to the paper itself rather than summarise them.

The publication is from 2008 (Scandinavian journal of clinical and laboratory investigation), a journal based in England.

More context: the Endothelin-1 compound page, all human trials.