NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsCyclic Adenosine Monophosphate Accumulation and beta-Adrenergic Binding in Unweighted and Denervated Rat Soleus MuscleUnweighting, but not denervation, of muscle reportedly "spares" insulin receptors, increasing insulin sensitivity. Unweighting also increases beta-adrenergic responses of carbohydrate metabolism. These differential characteristics were studied further by comparing cyclic adenosine monophosphate (cAMP) accumulation and beta-adrenergic binding in normal and 3-day unweighted or denervated soleus muscle. Submaximal amounts of isoproterenol, a p-agonist, increased cAMP accumulation in vitro and in vivo (by intramuscular (IM) injection) to a greater degree (P less than .05) in unweighted muscles. Forskolin or maximal isoproterenol had similar in vitro effects in all muscles, suggesting increased beta-adrenergic sensitivity following unweighting. Increased sensitivity was confirmed by a greater receptor density (B(sub max)) for iodo-125(-)-pindolol in particulate preparations of unweighted (420 x 10(exp -18) mol/mg muscle) than of control or denervated muscles (285 x 10(exp-18) mol/mg muscle). The three dissociation constant (Kd) values were similar (20.3 to 25.8 pmol/L). Total binding capacity (11.4 fmol/muscle) did not change during 3 days of unweighting, but diminished by 30% with denervation. This result illustrates the "sparing" and loss of receptors, respectively, in these two atrophy models. In diabetic animals, IM injection of insulin diminished CAMP accumulation in the presence of theophylline in unweighted muscle (-66% +/- 2%) more than in controls (-42% +'- 6%, P less than .001). These results show that insulin affects CAMP formation in muscle, and support a greater in vivo insulin response following unweighting atrophy. These various data support a role for lysosomal proteolysis in denervation, but not in unweighting, atrophy.Document ID19980213326Acquisition SourceAmes Research CenterDocument TypeReprint (Version printed in journal)External Source(s)doi:10.1016/0026-0495(92)90323-3AuthorsKirby, Christopher R.*(Arizona Univ. Tucson, AZ United States)*Woodman, Christopher R.*(Arizona Univ. Tucson, AZ United States)*Woolridge, Dale*(Arizona Univ. Tucson, AZ United States)*Tischler, Marc E.*(Arizona Univ. Tucson, AZ United States)*Date AcquiredSeptember 6, 2013Publication DateJuly 1, 1992Publication InformationPublication: MetabolismPublisher: W. B. Saunders CompanyVolume: 41Issue: 7ISSN: 0026-0495Subject CategoryLife Sciences (General)Report/Patent NumberNASA/CR-1992-205167NAS 1.26:205167Funding Number(s)CONTRACT_GRANT: NIH-NS-07309CONTRACT_GRANT: NIH-RR-05675CONTRACT_GRANT: NIH-HL-07249CONTRACT_GRANT: NAG2-384Distribution LimitsPublicCopyrightPublic Use Permitted.Available DownloadsNameType19980213326.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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