title: Lactate utilization and influx in resting and working rat red muscle.
abstract: 1. The behavior of lactate was studied during electrical stimulation and influx was measured under resting conditions of rat soleus muscle. 2. Lactate utilization was measured with (U-14C) lactate and results from electrical stimulation of the soleus muscle present evidence that this substance is mainly oxidized. 3. Under resting conditions, lactate influx showed a saturable transport system with an apparent Km of 11 mM. This low affinity for lactate suggests that lactate transport has a limiting factor for the muscle. 4. The increased lactate utilization under electrical stimulation (1,114 +/- 344 mumol/g/hr, at 20 mM lactate) corresponds to increased lactate permeability as compared to the influx rate (20.81 +/- 1.65 mumol/g/hr at 20 mM lactate) in resting conditions. 5. Alanine, epinephrine or S.I.T.S. 4-amino-4'isothiocyanostilbene-2-2'-disulphonate) do not affect lactate permeability in the soleus muscle.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002250:Carbon Radioisotopes; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007700:Kinetics; D007773:Lactates / Q000378:metabolism*; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D005082:Physical Exertion; D051381:Rats
chemical_list: D002250:Carbon Radioisotopes; D007773:Lactates