ABSTRACT
Title
Role of L-cysteine/hydrogen sulphide (H2S) pathway in the beneficial effect of ACE-inhibitor zofenopril on vascular funcion
Authors
A. Cantalupo
Doctorate in Scienza del Farmaco (XXV ciclo) (II year)
Dept. of Experimental Pharmacology – University of Naples Federico II, Naples-Italy
Doctorate in Scienza del Farmaco (XXV ciclo) (II year)
Dept. of Experimental Pharmacology – University of Naples Federico II, Naples-Italy
Abstract
Hydrogen sulphide (H2S), a well-known toxic gas, has been recognized as a signal molecule. In mammalian tissue, it is produced from L-cysteine by pyridoxal-5’-phosphate-dependent enzymes, cystathionine- β-synthase (CBS) and cystathionine γ-lyase (CSE) [1]. Both enzymes are widely distributed in tissues, however CBS is predominantly expressed in central nervous system whereas CSE is highly localized in the cardiovascular system [2]. In recent years, accumulating evidences have suggested that H2S is a new modulator in vascular homeostasis both in vivo [3] and in vitro [4]; moreover it has been observed that defective synthesis of H2S is involved in different vascular pathologies such as: hypertension [5], diabetes [6] and erectile disfunction [7].
Angiotensin converting enzyme (ACE) inhibitors are widely used in the treatment of arterial hypertension and cardiovascular diseases. However, it has been shown that ACE-inhibitors, beyond their classical action on renin-angiotensin system, exert a protective action on cardiovascular system. In fact they improve endothelial function, cardiac and vascular remodelling; reduce atherosclerosis [8] and vascular reactivity in a experimental model of diabetes [9]. Among all ACE inhibitors, it has been demonstrated that zofenopril have a better protective action than the others in different cardiovascular pathologies [10]. Therefore the aim of the study was to evaluate if the better action of zofenopril could be linked to the sulphydrilic group of its active metabolite zofenoprilat (Z) and to the L-cys/H2S pathway.
Male CD1 aortic rings were used for tissue bath experiments and cumulative- concentration curve of enalaprilat (E), zofenoprilat (S,S,S) and its diastereoisomer (R,S,S) were performed.
Z had a vasorelaxing effect that reached its maximum of 78.7±4.8% at 3mM. Also the diastereoisomer induced vasorelaxation but its effect was significantly lower compared to Z (Emax 43.9±8.1% vs. 78.7±4.8%, n=5; p<0.01). On the contrary, E did not induce any relaxation (19.7±2.3% vs. 78.7±4.8%,n=3; p<0.001, E vs Z respectively). Moreover the concentration-cumulative curve of Z was comparable to L-cys-induced vasodilatation (Emax 78.7±4.8% vs 78.2±4.8%, n=8, Z and L-cys respectively). Incubation of the rings with PAG (10mM), a specific CSE inhibitor, significantly reduced the Z-induced vasorelaxation implying the involvement of L-cys/H2S pathway in zofenoprilat action. In conclusion these data suggest that the vasorelaxant effect of zofenoprilat could be imputable to the interaction of this molecule with L-cys/H2S pathway, probably due to the sulphydrilic group present on its chemical structure. Moreover the interaction of Z with L-cys/H2S pathway seems to be stereospecific.
References
1. Abe and Kimura (1996)
2. Yap S et al. (2000) Semin Thromb Hemost 26: 335
3. Zhao W et al.(2003) Can J Physiol Pharmacol81: 848
4. Hosoki R et al.(1997) Biochem Biophys Res Commun237: 527
5. Yan H et al. (2004) Biocherm Biophys Res Commun 313: 22
6. Brancaleone V et al. (2008) Br J Pharmacol 15: 673
7. d’Emmanuele et al. (2009) Proc Natl Acad Sci USA 106(11): 4513
8. de Nigris F et al. (2001) Int J Cardiol 81: 107
9. Bucci M et al. (2009) Eur Urol 56: 378
10. Frascarelli S et al. (2004) J Cardiovasc Pharmacol 43: 294
Angiotensin converting enzyme (ACE) inhibitors are widely used in the treatment of arterial hypertension and cardiovascular diseases. However, it has been shown that ACE-inhibitors, beyond their classical action on renin-angiotensin system, exert a protective action on cardiovascular system. In fact they improve endothelial function, cardiac and vascular remodelling; reduce atherosclerosis [8] and vascular reactivity in a experimental model of diabetes [9]. Among all ACE inhibitors, it has been demonstrated that zofenopril have a better protective action than the others in different cardiovascular pathologies [10]. Therefore the aim of the study was to evaluate if the better action of zofenopril could be linked to the sulphydrilic group of its active metabolite zofenoprilat (Z) and to the L-cys/H2S pathway.
Male CD1 aortic rings were used for tissue bath experiments and cumulative- concentration curve of enalaprilat (E), zofenoprilat (S,S,S) and its diastereoisomer (R,S,S) were performed.
Z had a vasorelaxing effect that reached its maximum of 78.7±4.8% at 3mM. Also the diastereoisomer induced vasorelaxation but its effect was significantly lower compared to Z (Emax 43.9±8.1% vs. 78.7±4.8%, n=5; p<0.01). On the contrary, E did not induce any relaxation (19.7±2.3% vs. 78.7±4.8%,n=3; p<0.001, E vs Z respectively). Moreover the concentration-cumulative curve of Z was comparable to L-cys-induced vasodilatation (Emax 78.7±4.8% vs 78.2±4.8%, n=8, Z and L-cys respectively). Incubation of the rings with PAG (10mM), a specific CSE inhibitor, significantly reduced the Z-induced vasorelaxation implying the involvement of L-cys/H2S pathway in zofenoprilat action. In conclusion these data suggest that the vasorelaxant effect of zofenoprilat could be imputable to the interaction of this molecule with L-cys/H2S pathway, probably due to the sulphydrilic group present on its chemical structure. Moreover the interaction of Z with L-cys/H2S pathway seems to be stereospecific.
References
1. Abe and Kimura (1996)
2. Yap S et al. (2000) Semin Thromb Hemost 26: 335
3. Zhao W et al.(2003) Can J Physiol Pharmacol81: 848
4. Hosoki R et al.(1997) Biochem Biophys Res Commun237: 527
5. Yan H et al. (2004) Biocherm Biophys Res Commun 313: 22
6. Brancaleone V et al. (2008) Br J Pharmacol 15: 673
7. d’Emmanuele et al. (2009) Proc Natl Acad Sci USA 106(11): 4513
8. de Nigris F et al. (2001) Int J Cardiol 81: 107
9. Bucci M et al. (2009) Eur Urol 56: 378
10. Frascarelli S et al. (2004) J Cardiovasc Pharmacol 43: 294