Here's a pplausible hypothesis.
Whenever you take any drug that vasodilates the arterioles like angiotensin receptor blockers are claimed to do, a feedback loop kicks in to speed up the heart, sometimes dramatically (palpitations) and very quickly, to pump more blood. This effect can actually also raise BP somewhat nullifying the effect of the drug. I've been researching the effects of an old drug, hydralazine, acts directly to dilate the arterioles and there are warnings about the effect. Alas, the hydralazine doesn't do boop for me either much like ARB's and ACEI's.
Anyhoo, people who are high renin hypertensives and thus sensitive to ARB's and ACEI's will probably notice this effect. Nitroglycerine does it too.
What is in effect happening is that the heart, through evolution, mistakenly thinks that the body has suffered a major cut and is losing blood when the arteries open and it reacts accordingly in a effort to save the sufferer's life.
Last edited by Lenin; 11-04-2005 at 05:24 AM.