Background and purpose: Aminoguanidine (AG), an inhibitor of advanced glycation endproducts, has been shown to prevent arterial stiffening and cardiac hypertrophy in streptozotocin (STZ) and nicotinamide (NA)-induced type 2 diabetes in rats. Our aims were to examine whether AG produced benefits on cardiac pumping mechanics in the STZ and NA-treated animals in terms of maximal systolic elastance (E max ) and theoretical maximum flow (Q max ). Experimental approach: After induction of type 2 diabetes, rats received daily injections of AG (50 mg kg À1 , i.p.) for 8 weeks and were compared with age-matched, untreated, diabetic controls. Left ventricular (LV) pressure and ascending aortic flow signals were recorded to calculate E max and Q max , using the elastance-resistance model. Physically, E max reflects the contractility of the myocardium as an intact heart, whereas Q max has an inverse relationship with the LV internal resistance. Key results: Both type 2 diabetes and AG affected E max and Q max , and there was an interaction between diabetes and AG for these two variables. The E max and Q max were reduced in rats with type 2 diabetes, but showed a significant rise after administration of AG to these diabetic rats. Moreover, the increase in Q max corresponded to a decrease in total peripheral resistance of the systemic circulation when the STZ and NA-induced diabetic rats were treated with AG. Conclusions and implications: AG therapy prevented not only the contractile dysfunction of the heart, but also the augmentation in LV internal resistance in rats with STZ and NA-induced type 2 diabetes. (2008) 154, 758-764; doi:10.1038/bjp.2008 published online 31 March 2008 Keywords: advanced glycation end products; aminoguanidine; maximal systolic elastance; theoretical maximum flow; streptozotocin-nicotinamide diabetic rats Abbreviations: AG, aminoguanidine; AGEs, advanced glycation end products; E max , maximal systolic elastance; NA, nicotinamide; P isomax , peak isovolumic pressure of the left ventricle; Q max , theoretical maximum flow; R, internal resistance of the left ventricle; R p , total peripheral vascular resistance; STZ, streptozotocin; V eed , effective end-diastolic volume of the left ventricle British Journal of Pharmacology

The cardiac autonomic dysfunction in the absence of any significant changes in vascular dynamics, 4 but not 8 weeks after induction of type 2 diabetes, suggests that the diabetic autonomic neuropathy may precede arterial stiffening and cardiac hypertrophy in the STZ- and NA-treated rats.