  We demonstrate experimentally manipulation of supercurrent in Al-AlO_x-Ti
Josephson tunnel junctions by injecting quasiparticles in a Ti island from two
additional tunnel-coupled Al superconducting reservoirs. Both supercurrent
enhancement and quenching with respect to equilibrium are achieved. We
demonstrate cooling of the Ti line by quasiparticle injection from the normal
state deep into the superconducting phase. A model based on heat transport and
non-monotonic current-voltage characteristic of a Josephson junction
satisfactorily accounts for our findings.
