ET-3 and vasodilators

I didn't explain exactly what the clinical trial was for in my last post. The study title is, "Characterisation of the role of ETA and ETB receptors in regulating plasma ET-1 and the vasodilator response to ET-3 in man." A mouthful, yes. Pretty much what I am doing is taking 3 rounds of different medications spaced 3 weeks apart, and they do blood tests to see if the drugs are doing what they expect. One of the rounds is a placebo and the other two are already marketed drugs used for regulating blood flow in people that suffer from hypertension.
In some hypertension patients, especially with any kind of exertion, the vessels in the lungs contract making it more difficult for the heart to pump blood around the body, causing the right side of the heart to work harder. This in turn can lead to right-heart failure (heart attacks) and even death. The medications I am taking (apart from the placebo, of course) are designed to reopen or enlarge blood vessels, thereby reducing the amount of work the heart has to do and potentially saving the person's life.
The PhD student, whose nickname is Bean, running the study has found that these medications might also have positive effects on other organs (the liver or kidneys) and so is studying these effects on healthy patients - which is where I come in.
Monday was particularly intensive in that I had finished my week course of medication and they now needed to test the effects on a small test area of my body. They chose the forearm. They strapped diameter-sensitive mercury-filled bands around my forearm (to accurately test blood flow which meant I had to lie completely still for 2 hours) and pressure bands around my wrists and upper arm, inflating the wrist bands to the point that they cut off the circulation to my hands for upto 13 minutes at a time - I completely lost feeling in them during the intermittent testing over the course of the 2 hours. They then stuck (or tried to unsuccesfully a number of times) a needle in my artery to pump the ET-3 drug into my forearm. (ET-3 is a chemical that first causes a contraction of the blood vessels and then rewidens them.) During one of the unsuccessful attempts, they had already started testing when the needle was pushed out of the artery but remained in my arm - I have some damn strong arteries - so they were pumping this chemical into arm with it having nowhere to go, that was quite uncomfortable... Plus it meant they had to start again from scratch using my other arm, extending my hospital visit from 4 to 6 hours.
It wasn't long before the testing was over and I was glad to have the feeling and use of my hands back. Now I have a 2 week break and we start the whole procedure again with another medication. After the third round I get a nice little thankyou note with a few words and the number "£400." Another good thing about it is that I'm getting really used to seeing needles and my own blood coming out of my arm so to any more hospital visits I say, "Bring 'em on!"