Chilli receptors detect heart attack pain
I read the following article and I'm amazed that they are now planning to spend billions of dollars on finding a new drug to fill these receptor sites and relieve heart pain when cayenne pepper does the exact same thing and costs pennies!
- 15:42 03 September 2003
- NewScientist.com news service
- Daphne Chung
The same receptors that sense the burning taste of chilli peppers also sense chest pain during a heart attack, scientists have discovered.
The receptors are only present on the outer surface of the heart, which may explain why some "silent" heart attacks produce no pain. The new research also identifies a new target for drugs that alleviate chest pain caused by coronary heart disease, scientists say.
Vanilloid receptor 1 (VR1) is a pain sensor that is abundant in the skin and tongue and picks up the searing sensation of chilli peppers. Hui-Lin Pan, at Pennsylvania State University in the US, investigated whether it is also present in the heart.
"What was very striking was that we found the receptors were localised only on the surface of the heart," he told New Scientist. The outer surface was densely covered with VR1, but no receptors were detected on the inner surface.
"This is the first time anyone has documented these receptors in the heart," says Harold Schultz at the University of Nebraska Medical Center in Omaha.
Pan also found that VR1 was important in triggering the cardiac reflex response, which causes the chest pain associated with most heart attacks.
However, patients with silent ischaemia suffer damage on the inner surface of the heart. The lack of VR1 receptors on the inner surface could explain why no pain is felt.
VR1 could also be a target for drugs that reduce or prevent chest pain, Pan says. Schultz agrees: "If these receptors are involved in pain perception in heart attack, then it could open an avenue for looking for drugs that can block this pain."
Capsaicin, the pungent ingredient in chilli peppers, activates VR1. Previous studies had shown that, when applied to the heart surfaces of animals, capsaicin causes changes in blood pressure and heart rate similar to those seen in heart attacks. But the receptors involved in producing these changes were not known.
Pan used immunofluorescence labelling to show that VR1 was located on the outer surface of the heart. To determine whether the receptor was involved in the cardiac reflex response, he destroyed the nerves containing VR1 in one group of rats and compared their response with a group with intact VR1 receptors.
In the intact rats, both capsaicin and bradykinin - a chemical released during heart attacks - led to an increase in blood pressure and nerve activity. But in rats with no VR1, no increases were detected at all.
This surprised Pan. "We initially expected a partial response when we tried to trigger a reflex, because we thought other receptors would compensate for the lack of VR1." The absence of response suggests that VR1 is the most important receptor in chest pain.
Journal reference: Journal of Physiology (vol 551, p 515)