Comparison of haemodynamic responses to cilnidipine and nicardipine in an experimental model of acute congestive heart failure

Coronary Blood Flow Responses are Impaired Independent of NO and Endothelial Function in Conscious Dogs with Dilated Cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) is characterized by nitric oxide (NO) deficiency and endothelial dysfunction. Whether endothelium-independent vasodilation is preserved, particularly in the coronary circulation, remains controversial.

METHODS AND RESULTS

We studied systemic and coronary flow responses to the endothelium-dependent agonist, acetylcholine, the cGMP-dependent NO-donor, nitroglycerin, the predominantly endothelium-independent agonist, adenosine, the beta-adrenergic cAMP-dependent agonist, isoproterenol, and the calcium channel antagonist, nicardipine, in conscious dogs with pacing-induced DCM. Systemic blood flow response was impaired to acetylcholine but preserved to other vasodilators in DCM. In contrast, coronary blood flow response was significantly ( P < .05) depressed to all agonists. (Peak coronary blood flow response, control versus DCM: acetylcholine: 221 +/- 14% versus 156 +/- 11%; nitroglycerin: 220 +/- 17% versus 138 +/- 9%; adenosine: 635 +/- 65% versus 376 +/- 56%; nicardipine: 338 +/- 59% versus 115 +/- 23%; isoproterenol: 219 +/- 18% versus 86 +/- 20%). The attenuation was independent of systemic hemodynamic differences.

CONCLUSION

In contrast to systemic responses, coronary blood flow responses in DCM are impaired dependent or independent of NO or second messenger mechanisms, implying either distal signaling defects or structural abnormalities in the coronary vasculature.

N- and L-type calcium channel antagonist improves glomerular dynamics, reverses severe nephrosclerosis, and inhibits apoptosis and proliferation in an l-NAME/SHR model

OBJECTIVE

To determine the responses of the new dihydropyridine N- and L-type calcium antagonist, cilnidipine, on systemic and renal hemodynamics, glomerular dynamics, renal function, and histopathology in an Nomega-nitro-l-arginine methylester spontaneously hypertensive rat (l-NAME/SHR) model of nephrosclerosis.

METHODS

Five groups of 20-week-old male SHR were studied using renal micropuncture techniques and histopathological analyses: group 1, control; group 2, cilnidipine (10 mg/kg per day) by gavage, for 3 weeks; group 3, l-NAME (50 mg/l) in drinking water, for 3 weeks; group 4, combination of l-NAME and cilnidipine, for 3 weeks; group 5, l-NAME for 3 weeks, followed by cilnidipine for a subsequent 3 weeks.

RESULTS

Cilnidipine significantly reduced mean arterial pressure, total peripheral resistance and renal vascular resistance, while increasing effective renal blood flow and glomerular filtration rate (P < 0.01) in l-NAME/SHR. These hemodynamic changes were associated with significantly increased single nephron glomerular filtration rate (SNGFR) and plasma flow (SNPF) and decreased afferent glomerular arteriolar resistances when cilnidipine was used alone, and with increased SNGFR and SNPF, but decreased glomerular capillary pressure, afferent and efferent arteriolar resistances, urinary protein excretion, serum creatinine and uric acid concentrations (at least P < 0.05) in l-NAME-exacerbated SHR nephrosclerosis. In addition, glomerular and arteriolar injuries were markedly reversed (both P < 0.01), and glomerular apoptosis and cellular proliferation were inhibited and associated with glomerular tuft enlargement and an increase in cell number.

CONCLUSION

Cilnidipine not only prevented, but reversed, the severe renal hemodynamic and glomerular dynamic changes, including apoptosis and glomerular cellular proliferation, in l-NAME/SHR-exacerbated nephrosclerosis. This dual-channel calcium antagonist thus exerted renoprotective pathophysiological effects in the l-NAME/SHR.