Cultured myofibroblasts generate angiotensin peptides de novo. Role of patient factors in therapy resistance to antiproteinuric intervention in nondiabetic and diabetic nephropathy. Elevated vascular angiotensin converting enzyme mediates increased neointima formation after balloon injury in spontaneously hypertensive rats. Rx drugs

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J Mol Cell Cardiol. 1997 May;29(5):1375-86.
Cultured myofibroblasts generate angiotensin peptides de novo.

Katwa LC, Campbell SE, Tyagi SC, Lee SJ, Cicila GT, Weber KT.

Department of Internal Medicine, University of Missouri Health Sciences Center, Columbia 65212, USA.

Scar tissue found at the site of myocardial infarction (MI) contains phenotypically transformed fibroblast-like cells termed myofibroblasts (myoFb). In injured cardiac tissue, autoradiography and immunolabeling have localized high density angiotensin (Ang) converting enzyme (ACE) and Ang II receptor binding to these cells, suggesting that they may regulate local concentrations of Ang II and transduce signals at this site. Ang II is known to modulate type I collagen gene expression of fibroblasts and myoFb, and to promote fibrous tissue contraction, each of which may contribute to tissue repair. It is unknown whether myoFb themselves generate Ang peptides de novo via expression of angiotensinogen (Ao), an aspartyl protease needed to convert Ao to Ang I, and ACE. We therefore isolated and cultured myoFb from 4-week-old scar tissue of the adult rat left ventricle with transmural MI. In cultured myoFb we found: (a) immunoreactive membrane-bound ACE, cytosolic cathepsin D (Cat-D), and AT, receptors by immunofluorescence and confocal microscopy, (b) mRNA expression for Ao, ACE, and Cat-D, but not renin, by reverse transcriptase-polymerase chain reaction, (c) production of Ang I and II in serum-free culture media; (d) absence of renin activity; (e) a time-dependent conversion of Ao to Ang I by myoFb cytosol, which was inhibited by pepstatin A, but not by renin inhibitor; and (f) significant increase in Ang II production (P < 0.05) by exogenous Ao and Ang I (10 nM), which was significantly blocked by lisinopril (0.1 microM: P < 0.05). Thus, cultured myoFb express requisite components and are able to generate Ang I and II de novo. In an autocrine and/or paracrine manner, Ang II may regulate myoFb collagen turnover and fibrous tissue contraction.

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Kidney Int Suppl. 2000 Apr;75:S32-7.
Role of patient factors in therapy resistance to antiproteinuric intervention in nondiabetic and diabetic nephropathy.

Bos H, Andersen S, Rossing P, De Zeeuw D, Parving HH, De Jong PE, Navis G.

Department of Clinical Pharmacology and Division of Nephrology, University Hospital, Groningen, The Netherlands.

Reduction of proteinuria is a prerequisite for successful long-term renoprotection. To investigate whether individual patient factors are determinants of antiproteinuric efficacy, we analyzed individual responses to different modes of antiproteinuric intervention in nondiabetic and diabetic patients, obtained in prior studies comparing the efficacy of various pharmacological regimens. The individual antiproteinuric response to angiotensin-converting enzyme (ACE) inhibition positively correlated to the response to angiotensin type I (AT1) receptor blockade in diabetic (r = 0.67, P < 0.01, N = 16) as well as nondiabetic patients (r = 0.75, P < 0.01, N = 12). This corresponded to the correlations for antihypertensive efficacy between ACE inhibition and AT1 receptor blockade in diabetic (r = 0.73, P < 0.001) as well as nondiabetic patients (r = 0.55, P < 0.05). Remarkably, the antiproteinuric response to ACE inhibition also correlated positively to the antiproteinuric response to indomethacin (r = 0.63, P < 0.05, N = 9). Thus, patients responding favorably to one class of antiproteinuric drugs also respond favorably to other classes of available drugs, supporting a main role for individual patient factors in responsiveness or resistance to antiproteinuric intervention. In the search for strategies to improve response in these high risk patients, combination-treatment (combining different drugs, and combining drugs with dietary measures like sodium and protein restriction), and the use of higher doses may provide more fruitful strategies to optimize renoprotection than shifting to other classes of the available drugs.

online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10828759&dopt=Abstract

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J Hypertens. 1997 Jun;15(6):643-50.
Elevated vascular angiotensin converting enzyme mediates increased neointima formation after balloon injury in spontaneously hypertensive rats.

Jandeleit-Dahm K, Burrell LM, Johnston CI, Koch KM.

Department of Medicine, University of Hannover, Germany.

OBJECTIVE: To measure the effect of hypertension on neointima formation after balloon injury of rat aorta and its association with the local angiotensin converting enzyme (ACE) concentration. Balloon angioplasty of the thoracic aorta using a 2 French Fogarty catheter was performed in spontaneously hypertensive rats (SHR) and normotensive Sprague-Dawley (SD) rats. RESULTS: The injured aortic wall of SHR had already significantly higher ACE concentrations than did the uninjured aortic wall of normotensive SD rats (media: 729 +/- 37 dpm/mm2 in SHR versus 496 +/- 38 dpm/mm2 in SD rats, P < 0.01; intima: 83 +/- 5 dpm/mm2 versus 68 +/- 6 dpm/mm2 in SD rats, P < 0.01). Fourteen days after injury of the aorta the hypertensive rats had significantly higher neointima: media ratios than did the normotensive rats (0.83 +/- 0.09 versus 068 +/- 0.01, P < 0.01). This was associated with a significant increase in vascular media and neointima ACE concentrations in SHR (media 965 +/- 25 dpm/mm2, neointima 614 +/- 48 dpm/mm2) compared with those in normotensive SD rats after balloon angioplasty (media 669 +/- 23 dpm/mm2, neointima 287 +/- 33 dpm/mm2, P < 0.01). ACE inhibitor treatment with 10 mg/kg body weight lisinopril daily for 14 days by gavage reduced neointima proliferation in hypertensive and normotensive rats (neointima: media ratio: 0.35 +/- 0.02 for SHR, P < 0.01, versus untreated SHR with balloon injury; 0.28 +/- 0.01 for SD, P < 0.01, versus untreated SD rats with balloon injury). This was associated with significant vascular media ACE inhibition (SHR 149 +/- 9 dpm/mm2; SD rats 118 +/- 7 dpm/mm2; P < 0.01 versus untreated controls with balloon injury) and neointima ACE inhibition (SHR 73 +/- 4 dpm/mm2, SD rats 63 +/- 7 dpm/mm2, P < 0.01, versus untreated controls with balloon injury), but also lowered the blood pressure in SHR significantly (to 148 +/- 5 mmHg, P < 0.01, versus untreated SHR with balloon injury). When this drop in blood pressure was prevented by feeding the rats a high-salt diet (SHR with ACE inhibitor plus high salt-diet group blood pressure 193 +/- 3 mmHg, P = 0.57, versus untreated SHR) hypertension per se without the local ACE increase (ACE concentration in SHR with ACE inhibitor high-salt diet rats' media 167 +/- 10 dpm/mm2 and neointima 81 +/- 9 dpm/mm2) had only a mild effect on neointima formation after balloon angioplasty (neointima: media ratio 0.4 +/- 0.01 for SHR with ACE inhibitor plus high-salt diet versus 0.35 +/- 0.02 for SHR with ACE inhibitor plus normal-salt diet P < 0.05). Treatment with 10 mg/kg body weight angiotensin II subtype 1 receptor antagonist losartan potassium daily for 14 days by gavage was associated with a reduction in neointima formation similar to that observed with the ACE inhibitor both for SHR and for SD rats (neointima: media ratio 0.32 +/- 0.04 for SHR with losartan, 0.27 +/- 0.03 for SD rats with losartan; P < 0.01, versus untreated controls with balloon injury) suggesting that ACE inhibitor prevented neointima formation, at least in part by, reducing the local production of angiotensin II. CONCLUSION: Neointima formation after balloon angioplasty in SHR is increased compared with that in normotensive SD rats. This is due mainly to there being a higher degree of activation of the renin-angiotensin system in the aorta of the SHR before and after balloon injury compared with that in normotensive SD rats measured in terms of the increased vascular ACE concentrations. Blood pressure alone had only a moderate effect on neointima formation.

online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9218184&dopt=Abstract

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