Utilization of a radioimmunoassay to detect the generation of Arg-Pro-Pro-Gly-Phe, a stable endproduct of bradykinin metabolism (from cultured rat aortic smooth muscle cells exposed to bradykinin).

The peptide hormone bradykinin is a mediator in many physiological and pathological processes. The generation and, to a limited extent, metabolism occur at the sites of action. The short half-life of bradykinin (approximately 15 s) renders measurements of its concentration in bodily fluids difficult.

Radioiodination of the stable metabolic fragment of bradykinin, RPPGF.

Arg-Pro-Pro-Gly-Phe (RPPGF, BK[1-5]), is a stable metabolite of the peptide hormone bradykinin. Considering the short half-life of bradykinin (BK, approximately 15 secs), RPPGF has been used as a marker for BK's endogenous generation. A lack of a radioiodinated RPPGF has precluded the development of a radioimmunoassay for this peptide.

A metabolic fragment of bradykinin, Arg-Pro-Pro-Gly-Phe, protects against the deleterious effects of lipopolysaccharide in rats.

Extensive research has provided few therapeutic agents for the treatment of septicemia. Bradykinin, an endogenous vasodepressor hormone, is a key mediator in the hypotension seen with septicemia. The present investigation shows that a stable metabolic fragment of bradykinin, arginine-proline-proline-glycine-phenylalanine (RPPGF), prevents the deleterious effects of endotoxin [lipopolysaccharide (LPS); a component of the membrane of Gram negative bacteria], the signaling agent responsible for the effects of septicemia, in both anesthetized rats and in isolated rat aortic segments.

Kallikreins, kinins and cardiovascular diseases: a short review.

Studies of kallikrein-kinin systems since the 1930's have now led to substantial insight into the importance of this vasoactive system in the regulation of cardiovascular and renal function. It now seems clear that before long, these insights will lead to new therapeutic attacks upon diseases of the cardiovascular system and kidneys. This survey of notable recent work also emphasizes the fact that few of these fascinating new findings would have been produced without the stimulus of the initial discoveries of Héctor R Croxatto.

Effect of chronic bradykinin B2 receptor blockade on blood pressure of conscious Dahl salt-resistant rats.

1. In this study 3 protocols were utilized to determine the role of endogenous kinins in the resistance of the inbred Dahl (Rapp) salt-resistant (SR/Jr) rats to high salt diet-induced blood pressure elevation. 2.

Bradykinin B2 receptor modulates renal prostaglandin E2 and nitric oxide.

Bradykinin and lys-bradykinin generated intrarenally appear to be important renal paracrine hormones. However, the renal effects of endogenously generated bradykinin are still not clearly defined. In this study, we measured acute changes in renal excretory and hemodynamic functions and renal cortical interstitial fluid levels of bradykinin, prostaglandin E2, and cGMP in response to an acute intrarenal arterial infusion of the bradykinin B2 receptor antagonist Hoe 140 (icatibant), cyclooxygenase inhibitor indomethacin, or nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) given individually or combined in uninephrectomized, conscious dogs (n=10) in low sodium balance.

Renin-angiotensin system modulates renal bradykinin production.

Previous studies have shown that sodium depletion is associated with an increase in renal kallikrein-kinin system activity. This system may play an important role in counterbalancing the renal effects of the renin-angiotensin system. In this study, we examined whether the renal renin-angiotensin system participates in the regulation of renal bradykinin (BK) levels during sodium depletion.

Bradykinin B2 receptor antagonist increases chloride and water absorption in rat medullary collecting duct.

This study tested the hypothesis that intrarenal kinins play a regulatory role in electrolyte excretion by altering Cl- absorption in the collecting duct. We measured Cl- and insulin concentrations in tubular fluid samples obtained from medullary collecting ducts (MCD) of Dahl/Rapp salt-resistant (SR/ Jr) rats by microcatheterization of ducts of Bellini before and after treatment with the bradykinin receptor antagonist HOE-140. Tubular fluid was obtained from paired terminal inner medullary (t-IMCD) and outer medullary (OMCD) collecting duct sites of the left kidney.

Kallikreins and kinins. Molecular characteristics and cellular and tissue responses.

Kallikrein-kininogen-kinin systems are now topics of widespread interest. The long-standing appreciation of their diverse pharmacological properties and biochemical characteristics is being supplemented by modern definitions of their cellular receptors' signal-transduction mechanisms and physiological and pathological roles. The assignment of important homeostatic responsibilities for kinins, including those in autocrine and paracrine signaling for skeletal and cardiac muscle energy metabolism, is now subject to definitive experimental evaluation via the availability of better kallikrein inhibitors, specific kinin receptor antagonists, and techniques of genetic manipulation.

Theodore Cooper Memorial Lecture. Kallikreins and kinins. Some unanswered questions about system characteristics and roles in human disease.

Kinins can affect many aspects of cellular function, but their roles in human homeostatic mechanisms and disease are just beginning to be understood. In this brief review, some of the interesting new observations about kallikrein-kinin system characteristics, roles in cell behavior, and aberrancy in diseases of relevance to readers interested in hypertension will be discussed. Along the way, questions raised by these observations will be posed.

Brain kallikrein-kinin system abnormalities in spontaneously hypertensive rats.

The objective of the present study was to determine whether the brain kallikrein-kinin system differs between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) and if so, whether any detected differences occur before the development of hypertension in SHR. We measured cerebrospinal fluid levels of various components of the system in adult and young prehypertensive SHR and WKY. Cerebrospinal fluid kinin concentration and appearance rate were higher in SHR.

Rat renal interstitial bradykinin, prostaglandin E2, and cyclic guanosine 3',5'-monophosphate. Effects of altered sodium intake.

Kinins generated intrarenally probably affect renal function by altering levels of various mediators and messengers, including prostaglandin E2 (PGE2) and cyclic guanosine 3',5'-monophosphate (cGMP). Using a microdialysis technique, we monitored levels of cortical and medullary renal interstitial fluid kinins, PGE2, and cGMP after 5 days of 0.15% (low), 0.

Stimulation of renal interstitial bradykinin by sodium depletion.

The ability to measure and detect change in renal bradykinin in situ would allow study of relations between local kinin production and renal function in hypertensive or diabetic disorders. A new renal interstitial microdialysis technique allowed collections of renal subcapsular interstitial fluid 2 weeks after microdialysis probe placement in conscious dogs (n = 5) on a normal sodium diet (50 mEq/day) and for 5 subsequent days on low sodium intake (10 mEq/day). Although interstitial bradykinin measured by radioimmunoassay (RIA) was undetectable (< 0.

Cerebrospinal fluid kallikrein in spontaneously hypertensive and desoxycorticosterone acetate-salt hypertensive rats.

Objective: To determine whether immunoreactive tissue kallikrein levels in cerebrospinal fluid (CSF) of spontaneously hypertensive rats (SHR) and desoxycorticosterone acetate (DOCA)--salt-treated hypertensive rats are elevated compared with normotensive Wistar-Kyoto (WKY) and Sprague-Dawley rats.

Design: The present study was designed to test the hypothesis that the activity of the brain tissue kallikrein-kinin system is enhanced in hypertensive states.

Methods: Age-matched 18- to 19-week-old SHR and WKY rats, and Sprague-Dawley rats treated for 6 weeks either with 2 mg/kg per day DOCA subcutaneously and 0.

Estimate of the genetic divergence between inbred Dahl salt-sensitive and salt-resistant rats.

Objective: The genetic divergence of inbred Dahl salt-sensitive (SS/Jr) rats from inbred Dahl salt-resistant (SR/Jr) rats and various other inbred strains was measured.

Design: Structural differences in DNA between strains were evaluated.

Methods: Genetic variants were sought (1) by restriction fragment length polymorphism (RFLP) analysis, using 19 DNA probes, (2) by the polymerase chain reaction around microsatellites and (3) by DNA sequencing.

Kinins as vasoactive peptides.

During the past year, a number of significant publications have provided data that clearly establish the basis for the important role of the tissue kallikrein-kinin system in cardiovascular control and renal function. These publications include a report of advances in techniques for system component measurement, reports of the localization of central bradykinin receptors and an alteration in the sensitivity of the central bradykinin system in hypertension, and a description of the effects of new kinin receptor antagonists on our understanding of endogenous and exogenous kinin-induced vasorelaxation and its possible alteration in hypertension. Several significant reports describe the potentiation of endogenous kinin action by kininase inhibitors and establish the important interaction between kininase activity and kinin control of blood pressure.

Regulation of bradykinin-induced chloride secretion in a human epithelial cell line.

The chloride secretory response to bradykinin in T84 cells is regulated. The efflux rate of 125I from these cells can be used to measure this response, and to demonstrate that the sensitivity to bradykinin varies with time in culture. The response in NuT84 cells is greater than that in T84, and can be blocked by the B2 receptor antagonist HOE-140.

Enhancement of kallikrein production and kinin sensitivity in T84 cells by growth in the nude mouse.

The production of tissue kallikrein and the short-circuit current (SCC) response in the human colonic epithelial cell line T84 to bradykinin have been studied. These cells produce true tissue kallikrein and secrete it into the growth medium, and addition of bradykinin results in a small increase in SCC. After growth of T84 cells as a xenograft in athymic (nude) mice (NuT84), however, the cellular concentration of the enzyme increases 38-fold, and the maximal change in SCC (delta SCC) induced by bradykinin increases 35-fold.

Regulation of renal kallikrein synthesis and activation by glucocorticoids.

The effects of endogenous and exogenous glucocorticoids on renal active and prokallikrein levels (ng/mg protein) and in vivo kallikrein synthesis rate were studied in the conscious rat. Within two hours after low dose methylprednisolone (MP, 0.0125 to 0.

Renal kallikrein and hemodynamic abnormalities of diabetic kidney.

The relationship between renal hemodynamic abnormalities and renal kallikrein activity was studied in streptozocin-induced diabetic rats. Diabetic rats were either not treated with insulin and had plasma glucose levels greater than 400 mg/dl (severely hyperglycemic diabetic [SD]) or were treated with 1.5-1.

Renal kallikrein responses to dietary protein: a possible mediator of hyperfiltration.

We studied GFR, RPF and renal kallikrein in rats fed 9%, 25%, or 50% protein (casein) diets for 8 to 13 days. CFR and RPF increased progressively with increasing dietary protein. Renal excretion of active kallikrein (microgram/day) was 128 +/- 9, 174 +/- 11 and 228 +/- 14 in 9%, 25%, and 50% protein-fed rats, respectively (P less than 0.

Sex steroid hormones are altered in essential hypertension.

Little is known about the relationship between blood pressure and endogenous sex steroid hormones in patients with essential hypertension. Studies in hypertensive men have described decreased androgens. Men with cardiovascular disease may have estrogen levels which are increased or similar to healthy controls.

Bradykinin stimulates electrogenic bicarbonate secretion by the guinea pig gallbladder.

We studied bradykinin effects upon electrogenic ion transport across voltage-clamped guinea pig gallbladder, and found stimulation after both mucosal (EC50 = 0.2 microM) and serosal addition (EC50 = 10 microM). The mucosal effect is dose-dependent, reproducible and sustained.