Is there Ca2+(Sr2+)-3-hydroxybutyrate symport in rat-liver mitochondria? A reappraisal.
The observation in this laboratory that respiration and Sr2+ import were stimulated by the addition of 3-hydroxybutyrate to suspensions of N-ethylmaleimide-treated mitochondria respiring in state 6, after the addition of Sr2+, in a sucrose medium containing choline as substrate, led to the proposal by Moyle and Mitchell [(1977) FEBS Lett. 84, 135-140] that there is a Ca2+(Sr2+)-3-hydroxybutyrate symporter in rat liver mitochondria. However, experiments described in the present paper support a different interpretation. Under the conditions of the experiments by Moyle and Mitchell, the rate of respiration and the poise of Sr2+ accumulation are mainly limited, not by delta mu H+, but by lack of respiratory substrate. Even though N-ethylmaleimide is a potent inhibitor of 3-hydroxybutyrate dehydrogenase, we have found that, somewhat surprisingly, under the special conditions of these experiments, sufficient 3-hydroxybutyrate dehydrogenase activity remains available to account for the 3-hydroxybutyrate-dependent respiratory stimulation and Sr2+ import.
D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000494:pharmacology; D006884:Hydroxybutyrate Dehydrogenase / Q000037:antagonists & inhibitors; D006885:Hydroxybutyrates / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013324:Strontium / Q000378:metabolism*; D013997:Time Factors
D000090:Acetoacetates; D002087:Butyrates; D006873:Hydroquinones; D006885:Hydroxybutyrates; D012402:Rotenone; D020148:Butyric Acid; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000001:Calcimycin; C016635:acetoacetic acid; D006884:Hydroxybutyrate Dehydrogenase; D005033:Ethylmaleimide; C016421:duroquinol; D002118:Calcium; D020155:3-Hydroxybutyric Acid; D013324:Strontium