Lacidipine blunts early vascular activation in dyslipidemic hypertensives.

A J H - A P R I L 1 9 9 9 - V O L . 12, N O . 4, P A R T 2

POSTERS:

Vascular

Biology

C009

C010

TORASEMIDE INHIBITS ANGIOTENS1N II-INDUCED VASOCONSTRICTION AND INTRACELLULAR CALCIUM INCREASE IN THE AORTA OF SHR. A. Fortufio, P. Mufllz~, S. Ravassa, G. Zalba, M.A. Fortufio, J. Diez.* Vascular Pathophysiology Unit, School of Medicine, University of Navarra, Pamplona, Spain

MATRIX METALLOPROTEINASE-i 2 LEVELS IN HYPERTENSION: RELATIONSHIP TO LEFT V E N T R I C U L A R MASS, D I A S T O L I C DYSFUNCTION AND A N T I H Y P E R T E N S I V E T H E R A P Y F . L Li-Saw-Hee, A D . Blann, E. Edmunds, D.G. Beevers, G.Y.H. Lip. Haenaostasis, Thromlx~is and Vascular Biolo~ Unit, University Depamnent of Medicine, City Hospital, Birmingham, United Kingdom. Matrix metalloproteinas~ (MMP) are a family of malecules involved in the breakdown of collagen, which may be involved in the

Terasomide is a loop diuretic that is efficacious at low oncedaily doses in the treatment of arterial hypertension. As its , antihypertensive mechanism of action may not be entirely based on the elimination of salt and water from the body, a vasodilator effect of this drug can be considered. In the present study the ability of different concentrations of torasemide to modify angiotensin (ANG ll)-induced vascular tysponses was examined in endothelium-denuded aortic rings from spontaneously hipenensive rats (SHR) using an organ bath system. ANG II-induced increases of intracellular calcium concentration ([Ca2+]0 were also examined by image analysis in cultured aortic smooth muscle cells (VSMCs) from SHR. A dose-response curve to ANG 11 was plotted for cumulative concentrations (from 10 .9 to 10~ mol/L) in endothelium-denuded aortic rings (PD2: 7.5-+0.3). Isometric contraction induced by a submaximal concentration of ANG II (10 "~ tool/L) was reduced in a dose-dependent way by torasemide (ICed= 0.51±0.04 ttmol/L). Incubation of VSMCs with different concentrations orANG 11 (from 10"l° to 10"6 tool/L) resulted in a dose-dependem rise of [Ca2+]~ (pD2: 7.5_+0.3). The stimulatory effect of [Ca2+]~ induced by a submaximal concentration of ANG II (10 .7 tool/L) was blocked by torasemide (IC5o= 0.04±0.01 nmol/L). Our findings suggest that in vitro, torasemide inhibits the increase of [Ca2+]i induced by ANG I1 in VSMCs and blocks the vasoconstrictor action of the peptide. It is proposed that these actions might he involved in the in vivo observed antihypertensive effect of torasemide.

Key Words:

ANG II, calcium, smoothmusclecells, SHR, torasemide

pathogeneslsof vascu~ and cardiachypertrophy.To invesagatethis further, we measured levels of MMP Type 12 (MMP-12) using ELISA n g ~ m ~ in 32 patients with essential hypertension (16 males, mean age 60 S1~15 years), where 24 palaems were subsequently treated with antthypertensive therapy using enalapril or losartan. Results were compared to age- and sex-matched healthy controls. Our results are as follows: Healthy Hypertensive Parlors Controls Baseline 2 months post treatment Blood pressure 170±11/96!-_7 143_+13/85±7 MMP-12 ng/mL 750(200-2000) 90(40-500)* 66(40-750) LVM g 213±87 215±87 EtA ratio 0.79±0.35 0.79-20.39 ~ D , except for MMP-12, median (Inter-Quartile P,an~). *P<0.0001 for patients vs controls. Left ventricular mass (LVM) was correlated to baseline MMP-12 levels (Pea~0n r=0.41, P=0.041). No correlations were observed bctwe¢~ the Doppler E/A ratio (an index of diastolic function), blood pressure (in mmHg) and MMP-I2 levels. MMP-12 may be related to the pathogenesis of hypertension, left ventricular hypertrophy and diastolic dysfunction. Treatment with antihypertensive therapy did not significantly alter MMP-12 levels. Key Words: metalloproteinase, hypertension, left ventricular mass

C011

C012

ctTHROMBIN ACTIVATES PROTEIN KINASE C ISOFORM e IN A PERTUSSISTOXlN-SENSITIVE PATHWAY IN VASCULAR SMOOTH MUSCLE CELLS. S

LACIDIPINE BLUNTS EARLY VASCULAR ACTIVATION IN DYSLIPIDEMIC HYPERTENSIVES. (~. Fcrri, G. Desideri, E. Giuliani, M. Gentile ~, M. Pazienza, M. Pasin, R. Baldoncini, C. Bellini ~, A. Santuccif* I Clinica Medica- Cesalpino Foundation, University "La Sapienza', Rome, Department of Internal Medicine*, University of l'Aquila, Italy. In vitro, vascular cell adhesion molecule (VCAM)-I upregulation is induced by oxidized low density lipapmteins (LDL) and inhibited by lacidipine, a dihydmpyridine calcium.antagonist with antioxidant properties. To verify the effects of lacidipine on VCAM-I expression in vivo, circulating soluble VCAM-I levels were evaluated in 54 essential hypertensives with (16 M, 12F; Group I) and without (12 M, 14 F; Group II) elevated LDL-cholesteml levels, before and after 3 months on either lacidipine (2 or 4 mg/day), or atenol 100 rag/day or placebo treatments, given in randomized double-blind fashion. Blood samplings for assessment of plasma VCAM-I concentrations were repeated in Group I after further 3 months under aton,astatin treatments (20 mg/day), without discontinuing the above treatments. Baseline plasma VCAM-1 levels were higher in Group I (599.9i51.5) than in Group !I (523.14"52.1, p<0.0001). Only lacidiplne treatment reduced circulnting soluble VCAM-I leveht in Group l (Figure, P a n d A ) and, to a lesser extent, in Group II (lqgur~ Pand B). Addition of atorvastalin decreased serum LDL cholesterol in all patients, but ~luced plasma VCAM-I concentrations only in patients on atonol (from 610.2+.50.2 to 547.9-Y-51.7, p<0.01) and placebo treatments (from587.2.+.34.8 to 527.5±39.9, p<0.002). In conclusion, lacidipine ceunteractedA75° ] ~ ~ ~ VCAM-I upregdntion in dyslipi-.~ eoo I demic hypertensives and, to a lesser ~ 450 1 degree, in normolipidemic ones.~ 3oo~ Atorvastatin did not further redoce ~ 15o VCAM-I levels in lacidipine-u-eated o[ dyslipidemic patients, suggesting 1"3 Immlim that lacidipine blunted endothelial B 750- I ~lalterthem~ aeivati0n by inhibiting LDL a-e0o ~ 0.06

Seewald. U Schmitz, C Seul, Y Ko, A Sachinidis, H Vetter. Medizinische Universit~ts-Poliklinik, Wilhelmstrasse 35-37, 53111 Bonn, Germany ctThrombin is a potent vascular smooth muscle cell (VSMC) mitogen which growth effects are mediated by pertussistoxin (PTX) sensitive guanosine triphosphate (GTP) binding protein (Gi-protein). Activation of different protein kinase C (PKC) isoforms plays an important role in the regulation of growth in VSMC and seems to be regulated by Gq-coupled IP3-dependent mechanism. The aim of the present study was to investigate the effect of (~thrombin on activation of PKC isoforms ct, 1~,~ and ~ in VSMC and the involvement of PTX-sensitive Gi-Proteins. The activation of the PKC isoforms c~, [3, e and ~ was determined by measuring the distribution of the isoenzymes between the cytosolic and the particulate fraction by Western analysis. Cells were stimulated for different time periods (2, 5, 10, 15 and 30 min) with 5 nmol/L ctthrombin and fractionated by ultracentrifugation. 50p.g of total protein was loaded per lane, analyzed by 10% SDS-Page and Western blotting. The blots were visualized using Western-Light PlusTM protein detection kit and autoradiography. 5 nmol/L ctthrombin induced a translocation of PKC e isoform to the particulate fraction after 15 min to 431% (control=100%), whereas neither PKC ct nor PKG 13 and isoforms were affected. In PTX-preincubated cells (100ng/mL) a translocation of PKC ~ only to 272% occured. We conclude that ctthrombin selectively activates PKC E in a PTX-sensitive pathway.

Key Words:

thrombin, vascular smooth muscle cell growth, protein kinase C isoforms ct, [3, e,

,of iacidipine might Ixotect against ~ ~ 0 | the, development of atherosclerosis g ] in dys.lipidemic hypertensives g tSo Key Words: " 0| VCAM-I, lacidiplne, cholesterol I~,apme a t ~ a omtra

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