Concentration-response curves for endothelium-dependent vasorelaxation elicited by the cumulative application of ACh (A and C) and endothelium-independent relaxation by incremental concentrations of SNP (B and D) in isolated carotid arterial rings.

<p>(A) Effects of the NOS inhibitor L-NNA on the ACh-induced relaxation of carotid arterial rings from control and diabetic (STZ-induced) rats. Carotid arterial rings were preincubated with L-NNA (10⁻⁴ M; 30 min). (C and D) Effects of PLTs. ACh-induced (C) and SNP-induced (D) vasorelaxation of carotid arterial rings from controls induced for 30 min with PLTs isolated from control (Control PLTs) and diabetic (STZ PLTs) rats. Carotid arterial rings were preincubated with each type of PLT (1.65×10⁷ cells/mL; 30 min). Data are means ± SE; n = 5; <i>***P</i><0.001 vs. Control, <i>##P</i><0.01 or ###<i>P<</i>0.001 vs. Diabetic or +Control PLTs.