Evidence has been accumulating for some time that different glands of several mammalian species contain substances of protein nature which can have powerful vasodepressor effects. These substances can be readily extracted from the glandular tissues and appear in an active form in their secretions. It was only natural that these findings should lead to speculation, some of it quite early, about their possible physiological role. Thus, the first ideas about what are now known as the kinin systems were propounded under a different name. In their earliest definitive work, Kraut et al. (1930) had shown that extracts of pancreas and pancreatic juice owed their vasodepressor activity to a material of protein nature which they called kallikrein (see p. 2). Having found a similar substance in extracts of blood and urine, they put forward the idea that they were dealing with a new vasodilator hormone which was secreted by the pancreas, circulated in the blood stream in an inactive form, and then excreted. Physiological and clinical interest in this notion waned, but Werle and his colleagues carried on to show that, in part at least, the action of kallikrein was due to the release of a hypotensive substance from plasma (Werle et al., 1937; Werle and Berek, 1948).
The kallikreins have been defined as endogenous enzymes which rapidly and specifically liberate a kinin from plasma (Appendix on Nomenclature). Perhaps more comprehensively they might be defined as those proteolytic enzymes of animal origin which release a kinin from kininogen but, as far as is known, do not readily cleave peptide bonds in other proteins. The term kininogenase is a general one which has been applied to any enzyme that liberates a kinin from an inactive protein substrate. However, not all authors agree with this terminology, preferring to call all these enzymes kininogenins since to them the former expression implies the destruction of kininogen and the latter the formation (genesis) of active kinins (Rocha e Silva, 1962, 1963, 1965, and personal communication). For the purpose of this chapter the term kallikrein will be restricted to mammalian and avian kallikreins and will not include those enzymes found in snake venom, which may also be kallikreins (Iwanaga et al., 1965).
Terms like “tissue hormones” and “local hormones” were created (Feldberg and Schilf, 1930; Gaddum, 1936) almost before the class of the pharmacologically polyvalent and potent kinin hormones was discovered. The pioneers in the field of this subdivision of tissue hormones used essentially the same assay methods for the detection of the kinins that we do today. Frey and Kraut (1928) demonstrated by intravenous injection of urine in the dog the vasodilator activity of kallikrein. The contraction of smooth muscle was used by Werle et al. (1937) to show for the first time the liberation of a kinin by applying a mixture of human serum and an extract of salivary gland to an isolated segment of guinea pig ileum. The knowledge that the kinins were liberated enzymatically from the serum precursor kininogen was the result of studying the kinetics of the formation of kallidin (Werle and Berek, 1948) and of bradykinin (Rocha e Silva et al., 1949) by means of isolated smooth muscle preparations.
Plasma kinins can be released from the substrate globulins (kininogens) by enzymes which belong to the plasma proteins, and by enzymes derived from other tissues. We can therefore distinguish, by analogy with blood clotting, intrinsic and extrinsic plasma kinin formation.
There is general agreement that inflammation is a multimediated process. In previous chapters the participation of several endogenous substances as putative mediators of inflammatory reactions has been considered. In this chapter, evidence of the involvement of hypotensive kinins, and particularly bradykinin (Bk), in such reactions will be discussed. The main scope is to evaluate to what extent kinins are contributing to the inflammatory response, as well as to assess the significance of their participation in such a complex, multimediated process.
The discovery of kininogen dates back to the observation made by Werle et al. in 1937 that kallikrein by itself fails to contract isolated smooth muscular orrgans; addition of serum was necessary. Werle had already excluded a possible “cofactor” function of serum—the relationship between kallikrein and serum resembled that between enzyme and substrate. The second observation was made by Rocha e Silva et al. (1949) a decade later: they described a gut-stimulating principle in blood after application of snake venom in vivo or in vitro. From the historical point of view it is remarkable that both independent groups detected kinin activity only in combination with the kinin precursor. This applies to all the progress made in exploring the kinin system. Better knowledge of biochemistry and pharmacology of kinins contributed to our understanding of kininogen and vice versa. The definition of the term kininogen is unambiguous. It covers every protein that yields kinin(s) on incubation with suitable enzymes.
The transport of radiolabeled rat submandibular gland kallikrein was studied after local administration to the resting and activated rat submandibular gland. The iodinated kallikrein was electrophoretically, immunologically, and biologically indistinguishable from the intact enzyme. After intraductal and intraglandular application the radioactivity in venous effluent was quantitated and characterized. As judged by gel-filtration 125I-kallikrein in venous effluent eluted at a position similar to that seen when the iodinated enzyme was mixed with plasma, but earlier than the elution of 125I-kallikrein in buffer. In plasma, therefore, glandular kallikrein is probably bound to macromolecules. The radioactive fractions in venous effluent did not contain free iodine. Maximum concentration of 125I-kallikrein in venous effluent of resting glands was repeatedly reached about 20 min after intraductal administration. Moreover, the ductal epithelium represented the main permeation barrier since after intraglandular application the maximum venous 125I-kallikrein concentration was reached almost immediately. In activated gland (parasympathetic and sympathetic nerve stimulation), the venous 125I-kallikrein concentration was inversely related to glandular blood flow. We conclude that kallikrein present in the duct lumen or in the interstitium is able to reach the circulation, thereby making possible the local generation of plasma-kinins.
A substrate plasma for estimation of plasma kinin-forming enzyme activity in biological fluids has been prepared from human blood. Fresh citrated plasma was treated by a brief contact with a large amount of silicate powder, followed by heating to 56 degrees C for 1 hr, and finally by lowering its pH to 2 for 10 min. As an alternative to the final treatment with acid, disodium edetate was added to the plasma. The resulting final plasma did not show "spontaneous" plasma kinin activity on contact with glass, contained no kininase activity and did not inhibit plasma kinin enzyme activity of added specimens. The content of plasma kinin precursor in this final plasma was such that it could yield an amount of plasma kinin which corresponded to between 1 and 4 mug of synthetic bradykinin/ml.
Small infusions of dextran fractions having average molecular weights ranging from 10,600 to 412,000 yield plasma to lymph concentration ratios which are directly proportional to molecular weight. The concentration gradient for a specific molecular weight, however, decreases as the volume of infusion is increased. This volume effect, explained in terms of stretching of capillary pores, consequently provides less resistance to the passage of macromolecules through the capillary wall. The significance of these results in terms of the conventional pore theory of capillary permeability is discussed.
Le contenu en kinines du sang veineux ou artriel humain quivaut 0.1 mcg de bradykinine par 100 ml. Le contenu des veines du pli du coude n'augmente pas pendant la vasodilatation thermique ni pendant le travail des muscles de l'avant-bras.
Kininase activity is present in saliva obtained from the oral cavity but not in saliva obtained by cannulation of the parotid or submandibular ducts. This activity originates from squamous epithelial cells from the oral mucous membranes. Experiments with various inhibitors indicated that the kininase activity of squamous epithelial cells differs from that of plasma, and resembles that of erythrocytes. Kinin-forming activity is present both in the glandular secretion and in the squamous epithelial cells.
1. The protein and lipid composition of dog, cat, rabbit and rat lymph collected from various ducts were studied by zone electrophoresis and chemical analysis. 2. All the protein and lipoprotein fractions present in the plasma could be identified in the lymph, but were present in lower concentrations. The plasma‐lymph gradients for proteins and for lipids were similar, and were greater in the cervical duct lymph than in the thoracic duct lymph. 3. During fat absorption, the large increments of fat appearing in the thoracic duct lymph could be removed by high‐speed centrifugation (20,000 g) without significant alteration to the post‐absorptive lymph protein and lipoprotein electrophoretic patterns. 4. The possible ways in which this particulate fat, which enters the blood stream from the thoracic duct during fat absorption, escapes from the circulation have been discussed. The finding that the lymph from the cervical and leg ducts contains some chylomicrons which are greater in number during alimentary lipæmia suggests that some chylomicrons may escape through the capillary membrane without degradation to smaller lipid‐protein complexes.
Some pro affect smooth muscles and blood vessels. p. 241 London Capillary permeability to macromolecules Effect of anesthesia on lymph flow (local
J M Yoffey
F C Courtice
H S Mayerson
SCKACHTER, M. (1960). Some pro affect smooth muscles and blood vessels. p. 241. London: Pergamon Press. YOFFEY, J. M. & COURTICE, F. C. (1956). Edward Arnold Ltd. WASSERMAN, K., LOEB, L. & MAYERSON, H. S. (1955). Capillary permeability to macromolecules. Circulat. Res., 3, 594-603. Effect of anesthesia on lymph flow (local J. Pharmac. exp. Therap., 78, 400-406. rties ofkallidin, bradykinin and wasp venom kinin. Polypeptides which Lymphatics, Lymph and Lymphoid Tissue, p. 236. London:
Plasma kinin-forming-enzyme activity in lymph after injury
EDERY, H. & LEwis, G. P. (1962). Plasma kinin-forming-enzyme activity in lymph after injury. J. Physiol. (Lond.), 163, 48-49P.
Substrates for plasma kiniL-forming enzymes in human, dog and rabbit plasmas On a blood coagulation-retarding effect of rabbit lymph. Scand
S 1 Jacobsen
S A W Sele
B A Waaler
JACOBSEN, S. (1966). Substrates for plasma kiniL-forming enzymes in human, dog and rabbit plasmas. Br. J. Pharmac. Chemother., 26, 403-41 1. JACOBSEN, S., SELE, S. A. W. & WAALER, B. A. (1965). On a blood coagulation-retarding effect of rabbit lymph. Scand. J. clin. Lab. Invest., 17 (suppl. 84), 40-51.
Some pro rties of kallidin, bradykinin and wasp venom kinin. Polypeptides which affect smooth muscles and blood vessels. p. 241. London: Pergamon Press Capillary permeability to macromolecules
J M Yoffey
F C Courtice
SCKACHTER, M. (1960). Some pro rties of kallidin, bradykinin and wasp venom kinin. Polypeptides which affect smooth muscles and blood vessels. p. 241. London: Pergamon Press. YOFFEY, J. M. & COURTICE, F. C. (1956). Lymphatics, Lymph and Lymphoid Tissue, p. 236. London: Edward Arnold Ltd. WASSERMAN, K., LOEB, L. & MAYERSON, H. S. (1955). Capillary permeability to macromolecules. Circulat. Res., 3, 594-603.
Lymph and plasma kinin formation
JACOBSEN, S. & WAALER, B. A. (1965). Lymph and plasma kinin formation. J. Physiol. (Lord.), 177, 52-53P.
Glass activation of plasma or lymph was carried out by agitating equal volumes of such samples and glass beads (ballotini) of diameter 0.1 mm for 3 min as described by Margolis
KININOGEN, K4LLIKREIN AND KININASE IN LYMPH Glass activation of plasma or lymph was carried out by agitating equal volumes of such samples and glass beads (ballotini) of diameter 0.1 mm for 3 min as described by Margolis (1958).