KININOGENS::
Kininogens are the precursors of kinins they are present in plasma lymph and interstitial fluid three kinins have been identified in mammals:bradykinin lysylbradykinin (kallidin) methionyl-lylbradykinin these kinins are found in plasma
kinins produce arterial vasodilatation in several vascular beds including heart kidney intestine skeletal muscles and liver in this respect they are 10 times more potent than histamine further this action is possibly mediated through prostaglandin E2 and I2 the action of kinins is of very short duration because of arterial vasodilatation they produce a fall in blood pressure in veins kinins produce venoconstriction mediated by prostaglandins F2a
Prekallikreins (in liver)
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Trypsin Hageman factor
Kallikreins
(in plasma interstitial cells sweat glands
salivary glands pancreas
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kininogen_________kinins (Bradykinin kallidin methionyl bradykinin)
kinins also play an important role in the mediation of inflammation the function of kinins in other tissues is not clear
Recently the Angiotensin converting Enzyme inhibitors like captopril ramipril and teprotide have been found to enhance the degradation of the enzymes metabolizing kinins i.e kininase -I and kininase -II. Half life of kinins is about 15 seconds
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