Minute ventilation varied significantly among congenic mice. Mice with leptin dysfunction (ob/ob and db/db) had the lowest minute ventilation (means ± SD ml/min/g body weight). B6 = C57BL/6J; db/db = B6.BKS(D)-Lepr^db/J; DIO = B6 with diet-induced obesity; ob/ob = B6.Cg-Lep^ob/J.