Role of endothelin-1 in choroidal blood flow regulation during isometric exercise in healthy humans

What Was Tested

This randomized controlled trial paper looks at Endothelin-1.

There is evidence that the choroid has some autoregulatory capacity in response to changes in ocular perfusion pressure (OPP).

The mediators of this response are hitherto unidentified.

To test this hypothesis a randomized, double-masked, placebo-controlled, three way crossover study was performed in 12 healthy male volunteers.

Who Took Part

According to the abstract, 12 volunteers were involved.

The age groups tagged for this paper are adults, men only.

Subjects received on different study days intravenous infusions of the specific ET(A) receptor antagonist BQ-123, the angiotensin converting enzyme inhibitor enalapril or placebo.

During these infusion periods subjects were asked to squat for 6 minutes.

How the Study Was Run

The researchers set it up as a randomized, double-blind, placebo-controlled and crossover study.

The volunteers were allocated by chance, so the Endothelin-1 group and the comparison group should start out alike.

As a double-blind Endothelin-1 study, the assignments were hidden from both participants and investigators until the end.

Some volunteers received a placebo instead of Endothelin-1, giving a reference point.

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

Choroidal blood flow was measured using a confocal laser Doppler flowmeter and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure.

What Was Measured

PubMed files the paper under topics including Angiotensin-Converting Enzyme Inhibitors, Blood Flow Velocity, Blood Pressure, Choroid, Enalapril, Endopeptidases and Endothelin Receptor Antagonists.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Endothelin-1 in 12 volunteers.

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.

The abstract goes on to report its results in about 7 sentences; this page does not restate them, so read the paper for the findings and their limits.

The publication is from 2003 (Investigative ophthalmology & visual science), a journal based in United States.

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