ISSN:0008-4212    

DOI:10.1139/y79-001

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The thermal responses of three groups of control, 6-hydroxydopamine (6-OHDA) treated and 5,7-dihydroxytryptamine (5,7-DHT) treated rabbits to the administration of chlorpromazine (CPZ) were assessed at three different ambient temperatures (Ta: 2, 22, and 32 °C). Depleting catecholamines (CA) in brain with 6-OHDA produced a decrease in metabolic rate, in respiratory evaporative heat loss, and in ear blood flow at bothTa's of 2 and 22 °C, while depleting 5-hydroxytryptamine (5-HT) contents in brain with 5,7-DHT produced the opposite responses at the sameTa's. However, these amine-depleted animals maintained their rectal temperatures within normal limits over a wide range ofTa's tested. Furthermore, intraperitoneal administration of CPZ produced hypothermia at bothTa's of 2 and 22 °C. The major cause of the CPZ-induced hypothermia was an inhibition of metabolic heat production atTaof 2 °C. AtTaof 22 °C, the CPZ-induced hypothermia was due to both a decrease in heat production and an increase in ear blood flow. However, CPZ hypothermia was attenuated in the CA-depleted animals, but was potentiated in the 5-HT-depleted animals. The data indicate that brain monoamines are involved in the central mechanisms of CPZ-induced hypothermia.

ISSN:0008-4212    

DOI:10.1139/y79-002

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effect of pretreatment with penicillin on para-aminohippurate (PAH) transport by the kidney of the immature rat was evaluatedin vivo. After 3 days of penicillin administration, renal clearances of inulin (CIN), PAH (CPAH), and the renal tubular transport maximum (Tm) for PAH were measured in rats as young as 17 days of age. TheCPAHin 19- to 21-day-old rats pretreated with procaine penicillin was 54% greater than that of their littermate controls. Similarly,CPAHof rats that received sodium penicillin was 31% greater than control.CINwas not increased after penicillin pretreatment. Pretreatment of rats older than 24 days did not changeCINorCPAH. TheTmfor PAH of 17-day-old rats pretreated with sodium penicillin was 51% greater than that of control rats. It was concluded that pretreatment with penicillin enhances the renal secretion of organic anions by the immature rat.

ISSN:0008-4212    

DOI:10.1139/y79-003

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Fetal and neonatal rats received daily subcutaneous injections of 10 μg thyrotropin-releasing hormone (TRH) until 7 or 14 days postnatally. At 70 days the pups were challenged with 1 μg TRH intravenously via an indwelling jugular cannula. Basal serum thyroxine, triiodothyronine, and thyroid-stimulating hormone (TSH) concentrations did not differ among the three groups. The mean TSH responses as determined by the mean peak TSH concentration and the total TSH response as determined by planimetry were not significantly different, and there was no significant difference in pituitary TSH content following the TRH challenge among the three groups. This study suggests that the integrity of the hypothalamo–pituitary axis in adult rats cannot be affected by the repeated administration of pharmacologic doses of TRH during the perinatal period.

ISSN:0008-4212    

DOI:10.1139/y79-004

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Low concentrations of copper inhibited responses to norepinephrine and angiotensin (IC503 × 10−6 M) but not to potassium in rat mesenteric vascular preparations perfused either with buffer or indomethacin and prostaglandin (PGE2). The dose–response curve was not shifted by indomethacin, imidazole, or PGE2but was moved to the right by 2.8 × 10−11 MPGE1and to the left by 2.8 × 10−7 MPGE1. These effects of copper are similar to the effects of PGI2in the preparation. Copper moved the PGI2dose–response curve against noradrenaline in parallel to the left, suggesting that the two were interacting at some point. Penicillamine, which may stimulate PGE1synthesis, had PGE1-like interactions with the copper effect, suggesting that its value in Wilson's disease may be partly due to antagonism of the biological action of copper as well as to its copper-chelating properties.

ISSN:0008-4212    

DOI:10.1139/y79-005

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Since many α-adrenoceptor blocking drugs are known to have muscarinic blocking activity, BHC, a newly synthesized tetramine disulfide with α-adrenoceptor blocking activity, and two of its analogs were tested for muscarinic blocking activity in the isolated guinea pig atrium and ileum.BHC had muscarinic blocking activity. Its potency was higher in the atrium than in the ileum. The cardiac muscarinic blocking potency of the analog that contained carbon atoms instead of sulfur atoms was similar to that of BHC. Lower concentrations of the drugs antagonized inotropic effects of acetylcholine competitively, but higher concentrations had a smaller effect than expected for competitive antagonism.In the atrium BHC competitively inhibited the muscarinic blocking effect of atropine. Its atropinic blocking potency was smilar to the muscarinic blocking potency.Quinidine and gallamine also had muscarinic blocking and atropinic blocking effects in the atrium but were about 10 times less potent than BHC.

ISSN:0008-4212    

DOI:10.1139/y79-006

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The antiallergic properties of AY-25,674 were studied in a model of passive lung anaphylaxis. AY-25,674 caused a dose-related inhibition of antigen-induced bronchoconstriction in the passively sensitized rat. AY-25,674 was found to be twice as potent as disodium cromoglycate (DSCG) when injected intravenously. The oral administration of AY-25,674 also effectively inhibited antigen-induced bronchoconstriction. A tachyphylactic effect of repeated administration was found when the rats were pretreated with a large dose of AY-25,674. The compound did not significantly antagonize the bronchoconstriction produced by 5-hydroxytryptamine. These results indicate that AY-25,674 is an orally effective antianaphylactic compound with a mode of action similar to that of DSCG in preventing allergic mediator release.

ISSN:0008-4212    

DOI:10.1139/y79-007

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Pregnant hamsters were given varying doses of 6-mercaptopurine (6MP) at various times during gestation. The fetuses were examined for both gross and histological malformations which showed that the toxic and teratogenic effects of 6MP were dose and time dependent. The most severe gross malformations induced by 6MP were cleft palate, micrognathia and agnathia, microglossia, short limbs, and gut herniation. Grossly normal appearing fetuses, treated during late gestation, showed malformations at the tissue and cellular level. The effects of 6MP in hamster was compared with other specis, and with other growth-supressive agents, and it was deduced that the teratogenicity of 6MP is species and tissue specific. Also, it was recommended that histological observations be made an integral part of the teratological safety analysis.

ISSN:0008-4212    

DOI:10.1139/y79-008

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Pressor reactivity to a variety of pressor agents after partial ganglionic blockade induced with hexamethonium was investigated in intact, in spinalized, and in chemically sympathectomized, spontaneously hypertensive rats (SHR). Responses of unanaesthetized 6-month-old SHR to noradrenaline, phenylephrine, and angiotensin after hexamethonium administration (32 mg/kg) markedly exceeded those of unanaesthetized, age-matched normotensive Wistar–Kyoto rats (WKR). Responses of anaesthetized SHR to noradrenaline after hexamethonium administration (16 mg/kg) were also increased at the hypertensive stages but not at the prehypertensive stages, when compared with those of anaesthetized normotensive Wistar rats of respective ages. In spinalized and chemically sympathectomized preparations after hexamethonium administration (16 mg/kg), noradrenaline produced equal increases in blood pressure in 6-month-old SHR and WKR. It is suggested that the functional sympathetic nervous system is important for the hyperreactivity of intact SHR.

ISSN:0008-4212    

DOI:10.1139/y79-009

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effects of ether, chloroform, and halothane on calcium accumulation and ATPase activity of rat heart microsomes and mitochondria as well as on myofibrillar ATPase activity were investigated. Chloroform and halothane depressed microsomal and mitochondrial calcium uptake and binding in a parallel fashion. Ether decreased microsomal calcium binding and mitochondrial calcium uptake to varying degrees, while mitochondrial calcium binding was slightly enhanced. Whereas ether had no effect, chloroform depressed microsomal and mitochondrial total ATPase activities and halothane decreased microsomal ATPase and slightly stimulated mitochondrial total ATPase activities. Halothane was found to depress myofibrillar Mg2+-ATPase and ether was capable of decreasing myofibrillar Ca2+-ATPase. Chloroform was seen to inhibit both myofibrillar enzymes. These results suggest that the cardiodepressant actions of volatile anesthetic agents may be due to alterations in the calcium accumulating abilities of microsomal and mitochondrial membranes while direct myofibrillar effects may contribute to the depression seen with relatively higher concentrations of anesthetics.

ISSN:0008-4212    

DOI:10.1139/y79-010

出版商:NRC Research Press    

年代:1979

数据来源: NRC