. The endocrine organs; an introduction to the study of internal secretion . rcumstance that they undergo dilatation, while all the othersystemic arteries are contracting; but that it is to a certain extent causedby a specific effect of one of the pituitary autacoids is probable from thefact that it may occur in the absence of any obvious arterial change. Moreover, an increased rate of flow is maintained after the blood-pressurehas come back to the level at which it stood before the injection. And theeffect of a second and subsequent doses of the autacoid administered soonafter the main result
. The endocrine organs; an introduction to the study of internal secretion . rcumstance that they undergo dilatation, while all the othersystemic arteries are contracting; but that it is to a certain extent causedby a specific effect of one of the pituitary autacoids is probable from thefact that it may occur in the absence of any obvious arterial change. Moreover, an increased rate of flow is maintained after the blood-pressurehas come back to the level at which it stood before the injection. And theeffect of a second and subsequent doses of the autacoid administered soonafter the main result of the first dose has passed off is again to produce anincrease in the urine flow (fig. 62), although the blood-pressure as the resultof these after-doses does not rise, or falls instead of rising, and althoughthe kidney volume may now be unaffected. This experiment clearly Effects of Extracts of Posterior Lobe of Pituitary 89 demonstrates that the autacoid affects not only the blood-veasels of theorgan, but also its secreting cells, which it renders more active (or more. 0 .0 ._ H o 3 •a f> O o O i—I c3 O M II ^§ 13 ^ il • !-• En V> QJ si C Ou i £ o !*• a> i O = ! -13 « C ~ 3 ^ > S permeable). The secretion must therefore in these circumstances be inducedby a direct chemical excitation of the renal cells by the autacoid, whichthus bears the same relation to the kidneys as is borne by the secretine ofthe duodenum to the pancreas. In this respect also the action of the auta- 90 The Endocrine Organs 03 < a -a CeS •§ coid of the pituitary is comparable to that of those drugs which act asspecific diuretics upon the secreting cells of the kidney, as distinguished from those which pro-duce diuresis by increas-ing the water contentof the blood or by merelyincreasing the generalblood-pressure. The diuretic actionof the pituitary autacoidis not antagonised byatropine. This may betaken as a sign thatit does not act throughnerves or nerve-endings,but direct
Size: 1221px × 2047px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1900, bookdecade1910, bookidendocrineorgansi00shar
