Impairment and restoration of response to TSH in dog thyroid slices after treatment with phospholipase A and lubrol PX.
Incubation of dog thyroid slices with phospholipase A (10-40 U/Ml) or Lubrol PX (0.08-0.4%) caused a diminution in the subsequent TSH effect on the tissue cyclic AMP level and glucose oxidation. The same treatment had no effect on the basal level of these parameters. When the phospholipase A or Lubrol PX-treated slices were rinsed intensively with a Krebs-Ringer bicarbonate buffer and then incubated at 37degreesC in the same buffer for a further 1 to 3 hours, responsiveness to TSH recovered progressively reaching almost completely that of the control slices. Again, these procedures were without any significant effect on the responsiveness of the control slices. The above results together with those reported previously suggest strongly that phospholipids are an essential component of the plasma membrane system by which TSH stimulates adenylate cyclase activity. In addition, these essential lipids in the membrane appear to be renewed rather efficiently in this tissue, thus securing the functional integrity of the thyroid in the face of various deleterious situations.
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004285:Dogs; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D010740:Phospholipases / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology*; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology*
D013501:Surface-Active Agents; D013972:Thyrotropin; D000242:Cyclic AMP; D010740:Phospholipases; D005947:Glucose