An airfoil comprising: a concave pressure wall extending radially from a base to a tip of the airfoil; a convex suction wall connected to the concave pressure wall at a leading edge and a trailing edge spaced axially from the leading edge; and a plurality of cooling channels extending radially between the base and the tip of the airfoil between the concave pressure wall and the convex suction wall and configured to receive a cooling fluid supply through the base of the airfoil, the cooling channels comprising: a leading edge channel extending radially toward the tip, wherein the leading edge channel is configured to be in flow communication with the cooling fluid supply at the base; a trailing edge channel extending radially from the base toward the tip, wherein the trailing edge channel is configured to be in flow communication with the cooling fluid supply at the base and a plurality of trailing edge apertures; a serpentine cooling circuit comprising: a first up-pass channel forward of the trailing edge channel and configured to be in flow communication with a supply channel through the base of the airfoil; a down-pass channel forward of and in flow communication with the first up-pass channel; and a second up-pass channel forward of and in flow communication with the down-pass channel; wherein at least the down-pass channel and the second up-pass channel comprise a generally triangular transverse cross-section shape; and characterized in that the leading edge channel extends from the base; and a dedicated up-pass channel is arranged between the leading edge channel and the second up-pass channel of the serpentine cooling circuit, wherein the dedicated up-pass channel extends radially from the base toward the tip and is configured to be in flow communication with the cooling fluid supply at the base. a concave pressure wall extending radially from a base to a tip of the airfoil; a convex suction wall connected to the concave pressure wall at a leading edge and a trailing edge spaced axially from the leading edge; and a plurality of cooling channels extending radially between the base and the tip of the airfoil between the concave pressure wall and the convex suction wall and configured to receive a cooling fluid supply through the base of the airfoil, the cooling channels comprising: a leading edge channel extending radially toward the tip, wherein the leading edge channel is configured to be in flow communication with the cooling fluid supply at the base; a trailing edge channel extending radially from the base toward the tip, wherein the trailing edge channel is configured to be in flow communication with the cooling fluid supply at the base and a plurality of trailing edge apertures; a serpentine cooling circuit comprising: a first up-pass channel forward of the trailing edge channel and configured to be in flow communication with a supply channel through the base of the airfoil; a down-pass channel forward of and in flow communication with the first up-pass channel; and a second up-pass channel forward of and in flow communication with the down-pass channel; wherein at least the down-pass channel and the second up-pass channel comprise a generally triangular transverse cross-section shape; and characterized in that the leading edge channel extends from the base; and a dedicated up-pass channel is arranged between the leading edge channel and the second up-pass channel of the serpentine cooling circuit, wherein the dedicated up-pass channel extends radially from the base toward the tip and is configured to be in flow communication with the cooling fluid supply at the base. a leading edge channel extending radially toward the tip, wherein the leading edge channel is configured to be in flow communication with the cooling fluid supply at the base; a trailing edge channel extending radially from the base toward the tip, wherein the trailing edge channel is configured to be in flow communication with the cooling fluid supply at the base and a plurality of trailing edge apertures; a serpentine cooling circuit comprising: a first up-pass channel forward of the trailing edge channel and configured to be in flow communication with a supply channel through the base of the airfoil; a down-pass channel forward of and in flow communication with the first up-pass channel; and a second up-pass channel forward of and in flow communication with the down-pass channel; wherein at least the down-pass channel and the second up-pass channel comprise a generally triangular transverse cross-section shape; and characterized in that the leading edge channel extends from the base; and a first up-pass channel forward of the trailing edge channel and configured to be in flow communication with a supply channel through the base of the airfoil; a down-pass channel forward of and in flow communication with the first up-pass channel; and a second up-pass channel forward of and in flow communication with the down-pass channel; wherein at least the down-pass channel and the second up-pass channel comprise a generally triangular transverse cross-section shape; and characterized in that the leading edge channel extends from the base; and a dedicated up-pass channel is arranged between the leading edge channel and the second up-pass channel of the serpentine cooling circuit, wherein the dedicated up-pass channel extends radially from the base toward the tip and is configured to be in flow communication with the cooling fluid supply at the base.