Jet injection through microneedles for large volume subcutaneous delivery.

Subcutaneous (SC) drug delivery offers several advantages over intravenous (IV) delivery including: self-administration, improved patient experience, and reduced treatment costs. Unfortunately, each SC delivery is currently limited to ∼ 2.25 mL with IV administration required when the delivery volume exceeds this value.

Experimental and modelling evidence of shortening heat in cardiac muscle.

Key Points: Heat associated with muscle shortening has been repeatedly demonstrated in skeletal muscle, but its existence in cardiac muscle remains contentious after five decades of study. By iterating between experiments and computational modelling, we show compelling evidence for the existence of shortening heat in cardiac muscle and reveal, mechanistically, the source of this excess heat. Our results clarify a long-standing uncertainty in the field of cardiac muscle energetics.

Muscle heat: a window into the thermodynamics of a molecular machine.

The contraction of muscle is characterized by the development of force and movement (mechanics) together with the generation of heat (metabolism). Heat represents that component of the enthalpy of ATP hydrolysis that is not captured by the microscopic machinery of the cell for the performance of work. It arises from two conceptually and temporally distinct sources: initial metabolism and recovery metabolism.