# Phosphodiesterase 4 (PDE 4) Inhibition Reduces Ischemia–Reperfusion-Induced Leucocyte Infiltration, Apoptosis and Mitochondrial Fission Markers in Mice Skeletal Muscles Four Hours After Ischemia Onset

## TL;DR

This study shows that inhibiting PDE 4 with Rolipram reduces harmful effects in mouse skeletal muscles during ischemia-reperfusion.

## Contribution

The study is the first to show that PDE 4 inhibition protects skeletal muscles from ischemia-reperfusion injury in mice.

## Key findings

- PDE 4 inhibition reduced leucocyte infiltration and mitochondrial fission markers in ischemia-reperfusion injured muscles.
- Rolipram treatment decreased apoptosis and improved antioxidant defense in skeletal muscles.
- Mitochondrial respiration remained unchanged despite reduced fission markers.

## Abstract

Peripheral arterial disease is a leading cause of amputation and/or death worldwide. Phosphodiesterase 4 (PDE 4) inhibitors demonstrated beneficial effects in ischemia–reperfusion (IR) settings, but whether PDE 4 inhibition protects skeletal muscle against IR deleterious effects is unknown. We therefore performed limb IR (two hours each) in twenty-one male Swiss mice (12–16-week-old) treated or not with Rolipram (1 mg/kg i.p. 30 min before ischemia and 5 min before reperfusion). The muscles were analyzed 4 h after the onset of ischemia. IR significantly increased leucocyte infiltration (93.13 ± 6.886 vs. 150.1 ± 18.38 cells/mg of muscle, p < 0.05) and apoptosis (Bax/Bcl2 ratio, +239%, p < 0.05), together with enhanced mitochondrial fission transcripts (+224% for Drp1, p < 0.01 and +368%, p < 0.0001 for Fis1), and decreased mitochondrial respiration and antioxidant defense. PDE 4 inhibition reduced leucocyte infiltration (150.1 ± 18.38 vs. 55.58 ± 13.83; p < 0.01) and apoptosis (+67%, NS) in association with reduced fission markers (+91% for Drp 1 and +111%, p < 0.05, for Fis 1). Muscle mitochondrial respiration did not improve. In conclusion, PDE 4 inhibition using Rolipram partly protected skeletal muscles against IR-induced deleterious effects. These data support further studies investigating the usefulness of leucocytes modulation in lower-limb IR and a potential beneficial effect of PDE 4 inhibition in peripheral arterial disease.