We have reported that bradykinin (BK) excretion is increased in severely diabetic rats, independent of the activity of the main renal kinin-forming enzyme, true kallikrein (KLK). To further ...investigate the relationship between renal BK excretion and renal KLK in diabetes we studied the regulation of the renal kallikrein-like gene, rat kallikrein 7 (rKLK7), as well as of the KLK encoding gene, rKLK1, in streptozotocin-induced (STZ) diabetic rats.
Experiments were performed in STZ-induced diabetic male Wistar rats and their non-diabetic controls (n = 7 each group). Twelve weeks after STZ injection, urinary KLK activity, glomerular filtration rate and total protein excretion were determined. After extraction of total renal cortical RNA, specific oligonucleotides were used to generate a reverse transcription-polymerase chain reaction (RT-PCR) products of renal cortical rKLK1 and rKLK7 messenger (m)RNA. Southern blot analysis of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes.
After 12 weeks, the rats showed hyperglycemia, proteinuria and a reduced glomerular filtration rate. Renal kininogenase was reduced, as indicated by a reduction in the expression of rKLK1, as well as of the KLK-related gene, rKLK7.
Our data show that the expression of the two principal renal KLK genes is downregulated in the renal cortex of STZ-diabetic rats. We suggest that under severe diabetic conditions the rise in urinary BK excretion is not related to activation of the renal kinin-forming enzyme system.
Background aims Mesenchymal stromal cells (MSC) are spindle-shaped plastic-adherent cells isolated from bone marrow (BM), adipose tissue and other organs, including the placenta. Autologous ...BM-derived MSC have been studied in animals with experimentally induced critical limb ischemia (CLI) as a model of end-stage peripheral vascular disease. While demonstrating therapeutic benefit, the use of these cells is limited by the need to surgically extract BM and the fear of thrombosis secondary to the use of granulocyte–colony-stimulating factor (G-CSF) to mobilize the cells. Methods We studied the use of placental-derived adherent stromal cells (ASC) in a standard limb ischemia model of male Balb/c mice. These placental-derived cells, termed PLX-PAD, share the adherence and marker expression of BM-derived MSC but lack their differentiation potential. PLX-PAD are isolated from human placenta following a Caesarean section and cultured in a bioreactor, termed the PluriX™ System. The PluriX™ System provides a three-dimensional (3-D) microenvironment that enables the large-scale growth of these cells. PLX-PAD are stable adhesive cells that can be expanded in vitro without the loss of phenotype and without showing signs of karyotypic changes. Results The intramuscular (i.m.) administration of PLX-PAD in our model significantly improved blood flow (BF) ( P = 0.0008), increased capillary density ( P = 0.021), reduced oxidative stress ( P = 0.034) and reduced endothelial damage ( P = 0.004), while increasing limb function versus the administration of a phosphate-buffered saline (PBS) control vehicle in the affected limb. Conclusions Allogeneic placental-derived ASC may provide an off-the-shelf supply of therapeutic cells that would need no histocompatible tissue matching and be potentially less expensive and considerably more convenient than BM or adipose-derived MSC.
To characterize the role of the kallikrein–kinin system in diabetic cardiopathy, we studied the effect of streptozotocin (STZ) on the regulation of the myocardial bradykinin (BK) receptors, the B1 ...and B2 type, and two tissue kallikrein genes, rat kallikrein 1 (rKLK1) and rKLK7, in severely hyperglycemic rats. Experiments were performed in STZ-induced diabetic male Wistar rats (n=7) and compared to controls (n=7). After extraction of myocardial total RNA, specific oligonucleotides were used to generate reverse transcription PCR (RT-PCR) products from myocardial rKLK1 and rKLK7 mRNA. Southern blot analyses of these RT-PCR products were hybridized with appropriate gene-specific oligonucleotide probes. Myocardial B1 and B2 receptor expression were analyzed by RNase protection assays using specific probes from the coding region of the receptor genes. Twelve weeks after diabetes induction, the rats were normotensive and hyperglycemic and polyuric. We observed an impairment of the main myocardial kinin-forming enzymes, indicated by a reduction of the expression of both, rKLK1 and rKLK7. At this time the myocardial expression of the B1 receptor was not detectable in either group. Thus, the B1 receptor does not play a regulatory role in either the healthy or in STZ-diabetic heart. In contrast, the B2-receptor expression was detectable but did not differ significantly in either group. The reduced synthesis of myocardial tissue KLK implies a reduced capacity to generate BK in diabetic rats. This reduction is not compensated by elevated BK receptor levels. We suggest that alterations of the KKS may contribute to myocardial dysfunction in diabetes mellitus.
The effects of intracerebroventricular (i.c.v.) pretreatment with selective NK
1
((±)‐CP 96,345), NK
2a
(MEN 10,207; MEN 10,376) and NK
2b
(R 396) tachykinin receptor antagonists on the ...cardiovascular and behavioural responses to i.c.v. substance P (SP) and neurokinin A (NKA) were studied in conscious rats.
SP and NKA (25 pmol) induced mean arterial blood pressure and heart rate increases of the same magnitude and duration. The cardiovascular responses to both peptides were accompanied by excessive face washing, sniffing, grooming and wet dog shakes.
The cardiovascular responses to SP but not to NKA were attenuated by pretreatment with a NK
1
receptor antagonist, (±)‐CP 96,345. Of the behavioural responses, only face washing was significantly inhibited.
The cardiovascular and behavioural effects of NKA but not of SP were significantly attenuated by pretreatment with the selective NK
2b
receptor antagonist, R 396.
The selective NK
2a
receptor antagonists, MEN 10,207 and MEN 10,376, did not affect the cardiovascular and behavioural responses to either SP or NKA.
These results suggest, firstly, that the cardiovascular and behavioural effects of i.c.v. SP are mediated by NK
1
receptors; secondly, that NKA injected i.c.v. does not interact with NK
1
receptors but with another type of tachykinin receptor which may belong to the NK
2b
subclass. These findings provide pharmacological evidence for the existence of functionally active NK
2
receptors in the rat brain.
Kinins are potent bioactive peptides formed by the enzymatic action of kallikrein on kininogens. The discovery that angiotensin-converting enzyme, which generates angiotensin II, is also a major ...degrading enzyme of kinins, gave rise to the hypothesis that kinin potentiation, in addition to angiotensin II reduction, may be involved in the therapeutic actions of angiotensin-converting enzyme inhibitors. Angiotensin-converting enzyme inhibitors have become important drugs in the treatment of hypertension, congestive heart failure, postmyocardial infarction, and diabetic nephropathy. Although angiotensin II reduction appears to be the predominant mechanism of the antihypertensive effect of chronic angiotensin-converting enzyme inhibitor treatment, the role of kinins in the antihypertensive effects of angiotensin-converting enzyme inhibitors seems to be renin dependent and cannot be generalized for all models of hypertension. On the other hand, at least under experimental conditions, various cardioprotective effects of angiotensin-converting enzyme inhibitors appear to be due to the potentiation of endogenous kinins, including improved cardiac function, structural changes following myocardial ischemia, and induction of capillary growth in hypertension-induced left ventricular hypertrophy.
PDF
