Abstract
It has been suggested by others that renal hemodynamic response to a adrenoceptor stimulation is greater in newborns than adults (Am J Physiol 226:796, 1974). To further characterize the development of a adrenoceptors, the renal vascular response to specific α1 and α2 adrenoceptor stimulation using Phenylephrine (Phe) (α1) and Guanabenz (Gb) (α2) was determined in chronically catheterized F (132-140 days gestation; term 145 days) and A. Phe (4.5×10−8M to 3.6×10−7M) or Gb (6.2× 10−7M to 5×10−8M) was infused intrarenally and % changes in renal blood flow (%ΔRBF) were measured using a Doppler flow probe. α2 mediated renal vasoconstriction was of smaller magnitude in F than A (p<.001 ANOVA); ED50F/ED50A 5.3:1. However, α1 mediated vasoconstriction was different only at the highest dose of Phe tested.
(*p<0.01, F vs. A, Newman-Keuls) In conclusion: 1) this study does not confirm previous observations of increased α-adrenoceptor activity during development, 2) post-synaptic α2 adrenoceptors are functional in F, and 3) the F response to α2 stimulation is less than A while α1 response tends to be similar, suggesting a difference in the ontogeny of α1 and α2 adrenoceptors.
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Matherne, G., Nakamura, K., McWeeny, O. et al. α1 AND α2 MEDIATED RENAL VASOCONSTRICTION IN FETAL (F) AND ADULT (A) SHEEP: ONTOGENY OF POST-JUNCTIONAL α ADRENOCEPTORS. Pediatr Res 21 (Suppl 4), 238 (1987). https://doi.org/10.1203/00006450-198704010-00428
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DOI: https://doi.org/10.1203/00006450-198704010-00428