While on the topic of blood pressure, it is interesting to know that the red fluid in red meat is not blood. Almost all blood is removed from meat during slaughter, for both red and white meat. A very small, trace amount of blood remains within the muscle tissue of meat from the store.
Red meats, such as beef, contain a good deal of water. Water mixed with a protein called myoglobin, makes up most of the red liquid. It is a protein, that stores oxygen in muscle cells, very similar to hemoglobin, which stores oxygen in red blood cells. Most animals with a high amount of myoglobin are considered to be red meat, while animals with low levels of myoglobin, like most poultry are considered white meat.
Chickens and Turkeys are generally considered white meat, however due to the fact that both use their legs extensively, their leg muscles contain a significant amount of myoglobin which causes their meat to turn dark when cooked. This is why they have both white meat and dark meat.
Meat remains pinkish-red if it has been exposed to nitrites. Packagers use this to artificially keep the meat looking pink, even after it has spoiled. Consumers associate pink meat as fresh even though the pink color has little to do with the freshness of meat. Trust your nose, not your eyes.