摘要:

Summary.In the toad,Bufo bufo(L), the survival and function of auto‐ and homografts of the pars distalis of the pituitary gland placed under the median eminence or under the recessus opticus of the brain were studied. The toads were supplied with the grafts after removal of the pars distalis or after hypophysectomy.All autografts were well vascularized and surviving. However, only the autografts under the median eminence receiving a vascular supply from the hypophysio‐portal system appeared normal and exerted functional activities, as judged from the condition of the skin and the length of survival of the recipient.The survival of homografts was limited. Such grafts placed under the median eminence were, however, functional during periods of up to 16 weeks. Homografts placed under the recessus opticus failed to exert the activities studied in the present work. The recipients of homografts at this site did not survive appreciably longer than toads with the pars distalis removed, and their skin showed abnormal keratinization.The observations support the assumption that in amphibians the functional significance of the hypophysio‐portal system is the same as in mammals. The importance of immunological reactions for the function of homografts of this endocrine gland is discussed.Our thanks are due to Mrs. Gunhild Nilsson for her skilled help with the histological work and to Miss Gunnel Christiansson for valuable technical assistance.This work has been supported by a grant from the Rockefeller Found

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01295.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary.The renal tubular excretion of injected histamine has been investigated according to a method which takes advantage of the renal portal circulation in the bird. It was found that in the hen histamine is effectively excreted by the tubules to an extent comparable with the secretion of phenol red.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01296.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary.The permeability of the guinea pig placenta to I131‐labeled thyroxine and inorganic I131has been studied. The pertinent foetal and maternal samples were taken 3 to 4 ½ hr. after the administration of the radioactive compounds in question. The result goes to prove that thyroxine does not permeate the placenta in the first hours after its administration. Under similar test conditions more radioactivity was observed in the foetuses than in the mother animal after injection of inorganic I1

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01297.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary.The biological action of l‐triiodothyronine, azo‐arsenophenyl‐triiodothyronine and azo‐sulfophenyl‐triiodothyronine was determined on the basis of their positively chronotropic effect on the isolated spontaneously beating rat auricle after a three days treatment of the animals with the substances in question. It is evident that triiodothyronine has an accelerating effect on the rate of beat similar to that of thyroxine. An effect of the same kind but weaker, could also be demonstrated with the azo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01298.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary.The mechanogram of isolated spontaneously beating auricle of hypothyroid (treated with I131), normal and thyroxinized rats was recorded at 4° C intervals over a temperature range of 25° to 41° C.The rate of beat in various preparations showed no qualitative differences as a function of temperature.The ability of heart muscle to increase the contraction force with falling temperature seems to presuppose the presence of thyroid action. Therefore the mechanical output of hypothyroid auricles was powerfully depressed by lowering the temperature.The weaker the thyroid activity, the longer the duration of the contraction period at a certain temperature. As a function of rate, the duration of contraction was independent of thyroid acti

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01299.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary and Conclusions.The lower and upper temperature limit for the spontaneous mechanical activity of the isolated auricle of hibernating (hedgehog and hamster) and non‐hibernating (rat and partly rabbit) mammals has been determined. Besides this, some observations have been made of the mechanogram of hedgehog and hamster auricle at various temperatures.It was found that:1) The isolated auricle of a hibernating mammal ceases to beat at a temperature (1.5° to 6° C) definitely lower than that of a non‐hibernating mammal (16° to 18° C on average).2) Irreversible heat standstill of a hamster and rat auricle was observed at about 46.6° C and 48.7° C respectively. This was preceded by irregularities in rhythm at about 2° C lower temperature. The hedgehog auricle stopped suddenly at about 37° to 40° C. This standstill was reversible.3) The rate of the hamster auricle was a linear logarithmic function of the temperature, contrary to the case with rabbit and rat auricles; this observation indicates species differences.4) The ratio duration of contraction to cycle length increased with rising temperature in the hedgehog auricle, which differs from the rabbit

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01300.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary.The effects of prolonged treatment with pilocarpine and Hö 9980 on the activity of acetylcholine splitting enzymes and on the sensitivity to acetylcholine and adrenaline in normal and denervated salivary glands of the cat were studied. Hö 9980, piperidino‐aethyl‐diphenylazetamid hydrochloride, Hoechst, is a substance with an atropine‐like action. The submaxillary glands were preganglionically denervated and the parotid glands postganglionically denervated.A. Subcutaneous injections of pilocarpine twice a day for 8—12 days were found to produce the following effects:I. Submaxillary glands:Sensitivity.The supersensitivity to acetylcholine regularly found after denervation was prevented in the submaxillary gland; the secretory effect of acetylcholine after treatment was even less than on normal non‐treated glands.Enzymic activity.The difference in cholinesterase activity between a denervated and an innervated gland was abolished.II. Parotid glands:Sensitivity.The denervation supersensitivity to adrenaline and acetylcholine of the postganglionically denervated parotid gland was lessened or abolished.Enzymic activity.The pronounced difference in cholinesterase activity between a postganglionically denervated and a normal parotid gland was almost abolished.B. Subcutaneous injections of Hö 9980 once a day for two weeks were found to produce the following effects:I. Submaxillary glands:Sensitivity.The sensitivity of the normal submaxillary gland to adrenaline was increased to about the level reached after denervation (confirming Emmelinand Henriksson1953).Enzymic activity.The relation in cholinesterase activity between a normal and a denervated gland was not materially affected.II. Parotid glands:Sensitivity.The secretory effect of adrenaline on the normal parotid gland was equal, after treatment with the drug, to the secretory effect on the postganglionically denervated gland; the difference otherwise brought about by denervation being abolished.Enzymic activity.No effect on the cholinesterase activity neither in the denervated nor in the normally innervated parotid gland could be demonstrated; the marked fall in enzymic activity after postganglionic denervation could still be found.The findings are discussed in relation to the theory claiming enzyme decrease as the cause of supersensitivity after

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01301.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary and Conclusions.The metabolic rate of Arctic ground squirrels was determined and found to be of the same magnitude as common in mammals.Determinations during sleep at night showed a reduction of the metabolic rate to about 50 per cent of the average daytime values.The squirrels seemed to tolerate environmental temperatures from — 30° to + 40° C well; at higher temperatures they only survived limited exposure (about 1 hour at + 50° C).The metabolic rate remained fairly constant at environmental temperatures from + 10° to + 50° C; at lower temperatures their activity and metabolic rate increased. Scholanderet al.(1950).In the fall, when the animals gained weight, high RQ's (from 1.0 to 1.4) were usually found the first hours after feeding, when the environmental temperature was above 0° C, and always when it was above + 20° C. At 0° C and lower, the RQ's were always “normal” (0.7 to 1.0). This effect of the environmental temperature on the metabolism which was found the first hours after feeding diminished rapidly after approximately 4 to 5 hours.In the following spring when the squirrels did not gain weight, changes in the environmental temperature did not af

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01302.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

Summary and Conclusions.Measurements of the body temperature of Arctic Ground Squirrels at varying environmental temperatures are described.On unrestrained animals the body temperature was found to be constant (between 36.5° and 39° C) at environmental temperatures from — 30° to — 30° C. Similar results have been obtained on other arctic mammals by Irvingand Krog(1954).At + 38° C a marked increase in body temperature (to about 41° C) was found, but the animals survived. Restrained animals showed a greatly reduced tolerance to cold; the heat tolerance was slightly

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01303.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1956.tb01304.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY