PubMed · 4265236
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W Garn. 1972. [Percutaneous absorption studies using corticoids].. https://pubmed.ncbi.nlm.nih.gov/4265236/
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The temperature dependence of in vitro permeation through human epidermal membrane (HEM) was determined for urea, mannitol, tetraethylammonium ion (TEA), and corticosterone. The effect of temperature upon HEM electrical resistance was also measured. The majority of the experiments involved measuring the permeability coefficients of a specific permeant at 27 degrees C and 39 degrees C for a given HEM sample, the electrical resistance was also measured at each temperature. Similar experiments were also conducted with a model synthetic porous membrane. The effect of temperature was quantitated as the ratio of the permeability at 39 degrees C to the permeability at 27 degrees C for each permeant. These ratios observed for HEM with urea, mannitol, and TEA as the permeants were 1.66 +/- 0.05, 1.76 +/- 0.14, and 1.71 +/- 0.11, respectively. The change in temperature was shown to have a similar effect upon the electrical conductance of the HEM samples. The observed ratio for corticosterone permeation was 4.5 +/- 0.4. The experimental ratios observed for the three polar/ionic permeants were shown to approach those obtained from the model porous membrane and differed greatly from the ratio observed for the more lipophilic corticosterone, indicating differences in the effective transport mechanism/pathway for these classes of permeants. The permeability of urea was also observed to be inversely proportional to the electrical resistance of the HEM samples; this relationship was shown to be independent of temperature over the temperature range studied. The temperature dependence data and the observed relationship between urea permeability and electrical resistance strongly support the existence of a porous permeation pathway through the HEM as an operative diffusional route for polar-ionic permeants.
In a large group of patients with untreated hypertension, excretion rates of tetrahydrocorticosterone (THB), allotetrahydrocorticosterone (alloTHB) and tetrahydro-11-dehydrocorticosterone (THA) were all significantly higher than in a group of matched normotensive controls. Using the sum of these metabolites as an index of corticosterone secretion rate suggests that this variable is also higher. The increase was small (all excretion rates remained within the normal range) and corticosterone has low glucocorticoid and mineralocorticoid potency calling the clinical significance of this finding into question. However, it is possible that in combination with mildly deficient 11 beta-hydroxysteroid dehydrogenase activity such increases in corticosterone levels might affect blood pressure.