Distinguishing Central from Peripheral Nervous System Effects of Drugs

Murphy DJ, Renninger JP, Coatney RW (2001) A novel method for chronic measurement of respiratory function in the conscious monkey. Journal of Pharmacological and Toxicological Methods 46 13-20 

Distinguishing Central from Peripheral Nervous System Effects of Drugs 

Murphy DJ, Joran ME, Grando JC (1995) A non-invasive method for distinguishing central from peripheral nervous system effects of respiratory depressant drugs in conscious rats. General Pharmacology 26(3) 569—575 

End-tidal C02 (peak expired C02) is measured for each breath with a microcapnometer (Microcapnometer, model 0151-003L, Columbus Instruments, Columbus, OH, USA). This microcapnometer is uniquely suited for measurement of expired C02 in rats and other animals with low minute volumes (200-400 mL/min) since it utilizes relatively low flow rates (5 or 20 cc/min) compared with the standard capnometers that require 150-200 cc/min. This capability is achieved by using a low pressure, high velocity principle for analyzing the sampled gas. Airflow to the microcapnometer is maintained at 20 mL/min and is collected through a Teflon catheter (I.D. = 0.76 mm). Carbon dioxide concentrations are measured spectrophotometrically 

To convert the percentage C02 values measured by the microcapnometer (in dry air and at room temperature) to partial pressure values of C02 present in the alveoli (PaC02), the following formula is used  

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I.F.4 Distinguishing Central from Peripheral Nervous System Effects of Drugs 147... 

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