High concentrations of 17beta -estradiol attenuate the exercise pressor reflex in male cats.
Previously, intravenous injection of 17beta-estradiol in decerebrate male cats was found to attenuate central command but not the exercise pressor reflex. This latter finding was surprising because the dorsal horn, the spinal site receiving synaptic input from thin-fiber muscle afferents, is known to contain estrogen receptors. We were prompted, therefore, to reexamine this issue. Instead of injecting 17beta-estradiol intravenously, we applied it topically to the L(7) and S(1) spinal cord of male decerebrate cats. We found that topical application (150-200 micro l) of 17beta-estradiol in concentrations of 0.01, 0.1, and 1 micro g/ml had no effect on the exercise pressor reflex, whereas a concentration of 10 micro g/ml attenuated the reflex. We conclude that, in male cats, estrogen can only attenuate the exercise pressor reflex in concentrations that exceed the physiological level.
Schmitt
Petra M
PM
Departments of Internal Medicine and Human Physiology, Division of Cardiovascular Medicine, University of California, Davis, California 95616, USA.
Kaufman
Marc P
MP
D000287:Administration, Topical; D000818:Animals; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D002415:Cats; D003655:Decerebrate State; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009994:Osmolar Concentration; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D013116:Spinal Cord
D004958:Estradiol