Patent Application: US-95238504-A

Abstract:
the invention provides a use of angiotensin -, or a functional part , derivative and / or analogue thereof , for the preparation of a medicament for enhancing cardiac function . for instance , left ventricular diastolic pressure , coronary flow , endothelial function and / or myocyte hypertrophy can he enhanced by a medicament of the invention . by enhancing cardiac function , the development of heart failure can he attenuated or prevented . the invention further comprises a pharmaceutical composition comprising angiotensin -, or a functional part , derivative and / or analogue thereof , and a carrier . a method for treating an animal suffering from , or at risk of suffering from , heart failure comprising administering to the animal a pharmaceutical composition of the present invention is also provided herein .

Description:
the animal research committee of the university of groningen approved this study . left coronary artery ligations were performed in 39 male sprague - dawley rats weighing 250 to 300 g ( harlan ; zeist , the netherlands ). 14 perioperative mortality was 49 %. two weeks after induction of mi , rats were randomly allocated to intravenous infusion of either ang -( 1 - 7 ) ( 24 μg / kg per hour ; n = 10 ) or saline ( n = 10 ) by osmotic minipumps ( alzet 2004 ). sham - operated controls ( n = 10 ) received saline . after eight weeks of treatment , hemodynamic studies were performed under isoflurane anesthesia with a microtip pressure transducer , 15 coronary flow was measured in a langendorff setup , 14 endothelial function was tested in isolated aortic rings , 14 and plasma ang -( 1 - 7 ) levels were measured by radioimmunoassay . 16 midventricular slices were processed for histochemical analysis . infarct size was determined on picrosirius red / fast green - stained sections and was expressed as the percentage of scar length of total left ventricular circumference . 14 rats with infarcts smaller than 20 % were excluded ( n = 3 for ang -( 1 - 7 ) and n = 1 for saline - treated rats ). capillary density was determined on sections stained with biotin - labeled griffonia siinplicifolia lectin i ( gsl - i ) and hematoxylin and was expressed as the number of capillaries per mm 2 . myocyte cross - sectional area was measured on hematoxylin / eosin - stained sections . data are presented as mean ± sem . statistical analysis between the groups was performed by one - way anova followed by bonferroni &# 39 ; s t test . differences in dose - response curves were tested by anova for repeated measures with greenhouse - geisser correction for asphericity . differences were considered significant at p & lt ; 0 . 05 . general parameters at the end of treatment are shown in table 1 . there was no difference in body weight among the three groups . infarct size did not differ between the ang -( 1 - 7 ) and saline - treated group , with an average of 33 %. left ventricular weight to body weight ratios were equally increased in both mi groups compared with sham - operated controls ( 17 %, p & lt ; 0 . 05 ). myocyte cross - sectional area was significantly increased after infarction and the increase was attenuated to a nonsignificant level by ang -( 1 - 7 ). capillary density was diminished in infarcted rats , but did not differ between the ang -( 1 - 7 ) and saline - treated groups . to confirm delivery of the peptide , ang -( 1 - 7 ) plasma levels were measured at the end of treatment . intravenous infusion of ang -( 1 - 7 ) increased plasma levels of the peptide 40 - fold compared with mi controls to 917 . 8 ± 194 . 1 pmol / l ( table 1 ). after eight weeks of treatment , cardiac function was measured in vivo in anesthetized rats . as expected , cardiac function was significantly impaired in untreated mi rats compared with sham - operated rats . in contrast , in ang . ( 1 - 7 )- treated rats , none of these parameters were significantly deteriorated , except the systolic dp / dt ( fig1 a and 1e ). coronary flow was measured ex vivo in a langendorff setup . when compared with sham - operated hearts , baseline coronary flow was decreased in untreated mi rats , whereas in ang -( 1 - 7 )- treated rats , baseline coronary flow was almost completely preserved ( fig1 f ). coronary endothelial function and maximal coronary flow were tested by a two - minute infusion of 3 × 10 − 8 mol / l bradykinin and 10 − 5 mol / l adenosine , respectively . bradykinin infusion evoked an increase in coronary flow in all three groups , but flow was still significantly lower in untreated infarcted hearts than in sham - operated hearts . bradykinin - dependent flow in ang -( 1 - 7 )- treated hearts was not significantly impaired . maximal flow after adenosine infusion was significantly decreased in untreated mi rats compared with sham - operated rats , as well . in ang -( 1 - 7 )- treated mi rats , the difference did not reach statistical significance ( table 2 ). endothelial dysfunction is a key feature in heart failure . 14 to examine the effects of ang -( 1 - 7 ) treatment on this aspect of cardiac failure , we investigated endothelium - dependent relaxation in isolated aortic rings . phenylephrine elicited similar contractile responses in all three groups ( data not shown ). the response to the endothelium - dependent vasodilator metacholine was markedly decreased in rings from infarcted animals to 58 . 4 %± 11 . 7 % ( p & lt ; 0 . 05 ) of sham - operated rats . in ang -( 1 - 7 )- treated rats , however , metacholine - induced relaxation was identical to sham rats ( p & lt ; 0 . 05 versus mi control ; fig2 ). the relaxation in response to the endothelium independent vasodilator nano 2 ( 10 − 2 mol / l ) was equal in the three groups ( data not shown ). in the present study , the effects of intravenous infusion of ang -( 1 - 7 ) on the development of cardiac function were examined in a rat coronary artery ligation model . we found that eight weeks of ang -( 1 - 7 ) treatment prevented the deterioration of cardiac function , as shown by a 40 % reduction in left ventricular end - diastolic pressure , an almost full preservation of coronary flow , and preserved aortic endothelial function . although ang -( 1 - 7 ) has weak vasodilator activities , 9 , 10 an increase in mean arterial pressure was found in the group infused with ang -( 1 - 7 ). moreover , myocyte hypertrophy was attenuated by ang -( 1 - 7 ) infusion . both results show an intracardiac mode of action of ang -( 1 - 7 ). this study shows that ang -( 1 - 7 ) is an effective agent in the attenuation of the development of heart failure after mi . 1 . pfeffer j . m ., pfeffer m . a ., mirsky i ., et al . regression of left ventricular hypertrophy and prevention of left ventricular dysfunction by captopril in the spontaneously hypertensive rat . proc . natl . acad . sci . u . s . a . 1982 ; 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