Interstate 635 (Texas) Interstate 635 (Texas) Interstate 635 (I-635) is a partial loop around Dallas, Texas, in the United States between I-20 in Balch Springs and State Highway 121 (SH 121) at the north entrance of the Dallas-Fort Worth International Airport in Grapevine. It intersects I-35E at exits 27B–C, but does not connect with I-35W. It is known locally as the Lyndon B. Johnson Freeway, or LBJ, named after Lyndon B. Johnson, the former U.S. Senator from Texas, 37th Vice President, and the 36th President of the United States. Where I-635 ends at I-20, I-20 continues the LBJ Freeway name heading west. Because
Referred pain modality, intensity, and timing of painful stimuli can be controlled with much more precision. Within this setting there are two main ways that referred pain is studied. In recent years several different chemicals have been used to induce referred pain including bradykinin, substance P, capsaicin, and serotonin. However, before any of these substances became widespread in their use a solution of hypertonic saline was used instead. Through various experiments it was determined that there were multiple factors that correlated with saline administration such as infusion rate, saline concentration, pressure, and amount of saline used. The mechanism by which the saline