Editorial Focus Carbon monoxide: vasoconstrictor or vasodilator? That’s the question

of renal heme oxygenase-1 (HO-1) attenuates afferent arte-rioles (Aff-Art) constrictor responses to increased renal perfu-sion pressure (RPP), thus suggesting that increased HO-1 modulates renal autoregulation in pathophysiological condi-tions. The authors elegantly made their conclusions by first showing the HO-1 pattern distribution following heme or SnCl2 treatment. In particular, the authors demonstrated that in hemin-treated rats HO-1 was expressed in tubular epithelial cells with prominent staining of proximal tubules, whereas in SnCl2-treated rats HO-1 was detected in medullary tubular epithelial cells and few proximal tubular cells. Interestingly, HO-1 was not detected in interlobular arteries or Aff-Art following heme or SnCl2 treatment (Fig. 1). This first set of experiments is consistent with previous studies suggesting the possibility of pharmacologically regulating HO-1 expressio