Relation of blood pH and CO₂ to central stimulatory effects of saline on dogs

¹ Department of Neurology, University of California Medical Center, San Francisco, California

Normal saline (0.9% NaCl, pH 5.85) infused intracisternally in dogs has a general excitatory effect on the central nervous system, producing increased rate and depth of respiration and increased muscular tone with muscle discharges, especially from facial, cranial, and neck muscles. This excitatory effect correlated most closely with changes in systemic pCO₂. being enhanced when the arterial pCO₂ was decreased and being depressed when the arterial pCO₂ was increased. This excitatory effect also can be depressed or abolished by relatively small concentrations of CaCl₂. Mode of action is discussed.

Key Words: intrathecal saline infusion • CNS stimulation • tetany • tetany induced by decreased arterial pCO₂ • low Ca tetany • independent of pH • tetany suppressed by increased arterial pCO₂

Submitted on December 7, 1962