PECAM1 and ischemia: CD31 immunostaining results indicated that stimulation of S1R increased microvascular density in the peri-infarct region (354.70 ± 34.49 vs. 193.30 ± 31.07 number/mm2, P < 0.01), with which co-localization of PCNA staining ascribed this increase to concomitant proliferation of endothelial cells, and the presence of mature vessels, as shown by α-SMA immunostaining (88.67 ± 8.62 vs. 48.33 ± 7.77 number/mm2, P < 0.005), was also indicative of an augmented blood supply to residual cardiomyocytes, thus counteracting PIHF-induced local ischemia (Fig. 4B and C).