“…The anaesthetized rat is being used increasingly for studies of respiratory control (Hanna, Drysdale & Cragg, 1979;Hori, Roth & Yamamoto, 1970;Laha, Nayar, Chhina & Singh, 1977;Lai, Tsuya & Hildebrandt, 1978;Malcolm, Sarelius & Sinclair, 1980). The effect of pentobarbitone on alveolar and arterial gas levels has been demonstrated (Cragg & Drysdale, 1979) but generally the effects of anaesthetic regimes in the rat have not been assessed to the same extent as in the rabbit (Korner, Uther & White, 1968; Blake & Korner, 1980), cat (Wang & Nims, 1948; F16rtz & Borison, 1%9) and dog (Ledsome, Linden & Norman, 1971).…”