Some recent advances in studies on J receptors.

While describing recent advances in studies on J receptors it was shown that the discovery of the principle of the relative dilution of multiple solutes in flowing fluids paved the way for developing a new method for measuring in vivo the concentration of injected drugs in the blood of the pulmonary artery. This led to the finding that excitatory solutes move out of the capillaries through a process of diffusion not through filtration. Increase in the permeability of the capillaries causes a marked increase in the responses of the J receptors to excitants by causing greater movement of the excitants to the receptors. This information is likely to yield a method for distinguishing permeability edema from hamodynamic edema in man. The most recent advance relates to the evidence showing conclusively that the sensations and dry cough produced by injecting lobeline intravenouly in man is due to the stimulation of the J receptors. The slowly and rapidly adapting receptors play little or no role in this. The nature of the sensations felt is somewhat variable, most commonly it is choking and pressure localised in the throat and upper chest. Similar sensations are felt by subjects with high altitude pulmonary edema (HAPE). From this data it is extrapolated that the same kinds of sensations that accompany breathlessness after moderate or severe exercise at sea level are also J receptor induced.