Elevating dietary salt exacerbates hyperpnea-induced airway obstruction in guinea pigs

1 School of Sport Science, Physical Education and Recreation, University of Wales Institute Cardiff, Wales CF23 6XD, United Kingdom; and 2 Department of Exercise and Health Science and 3 Department of Physiology, Colorado State University, Fort Collins, Colorado 80523 Previous studies have indicated that increased dietary salt consumption worsens postexercise pulmonary function in humans with exercise-induced asthma (EIA). It has been suggested that EIA and hyperpnea-induced airway obstruction (HIAO) in guinea pigs (an animal model of EIA) are mediated by similar mechanisms. Therefore, the purpose of this study was to determine whether altering dietary salt consumption also exacerbated HIAO in guinea pigs. Furthermore, the potential pathway of action of dietary salt was investigated by blocking leukotriene (LT) production during HIAO in guinea pigs. Thirty-two male Hartley strain guinea pigs were split into two groups. One group ( n = 16) of animals ingested a normal-salt diet (NSD) for 2 wk; the other group ( n = 16) ingested a high-salt diet (HSD) for 2 wk. Thereafter, animals were anesthetized, cannulated, tracheotomized, and mechanically ventilated during a baseline period and during two dry gas hyperpnea challenges. After the first challenge, the animals were administered either saline or nordihydroguaiaretic acid, a LT inhibitor. Bladder urine was analyzed for electrolyte concentrations and urinary LTE 4 . The HSD elicited higher airway inspiratory pressures (Ptr) than the NSD ( P