Structure and biological role of prostaglandin leukotrienes thromboxanes
Answers
leukotrienes, are collectively known as eicosanoids to reflect their origin
from polyunsaturated fatty acids with 20 carbons. They are
extremely potent compounds that elicit a wide range of responses,
both physiologic (inflammatory response) and pathologic (hyper -
sensitivity). They ensure gastric integrity and renal function, regulate
smooth muscle contraction (intestine and uterus are key sites) and
blood vessel diameter, and maintain platelet homeostasis. Although
they have been compared to hormones in terms of their actions,
eicosanoids differ from the true hormones in that they are produced in
very small amounts in almost all tissues rather than in specialized
glands. They also act locally rather than after transport in the blood to
distant sites, as occurs with true hormones such as insulin.
Eicosanoids are not stored, and they have an extremely short half-life,
being rapidly metabolized to inactive products. Their biologic actions
are mediated by plasma membrane G protein–coupled receptors