Effects of ether and pentobarbital anesthesia on thyroid function in the rat.

Studies were performed to examine the effect of two anesthetic agents, ether and pentobarbital, on the hypothalamic-pituitary-thyroid function in vivo. In non-anesthetized animals, plasma thyrotropin (TSH) increased rapidly from basal values of 0.1, a peak of 0.49 microng/ml, 25 min after exposure to the cold. Anesthesia with ether during exposure to the cold completely prevented the rise in TSH. During pentobarbital anesthesia, the rise in TSH after exposure to cold was reduced by more than 90%. Even a three minute period of ether anesthesia prior to cold exposure reduced the peak response to cold as well as delayed this response when compared to the untreated group. During two hours of anesthesia with ether, the TSH concentration declined in animals which were fed a low iodine diet at essentially the same rate as in animals on the same diet given an injection of 3 microng of triiodothyronine. Pentobarbital did not suppress TSH at room temperature. The release of thyrotropin after injection of synthetic thyrotropin-releasing hormone (TRH) was greater in animals anesthetized with pentobarbital than in controls and was slightly reduced in ether-anesthetized animals. This difference was observed when thyrotropin was given intraperitoneally or intravenously and the slope of the dose-response curves to TRH showed a flattening of the curve of rats treated with ether and a steeper slope of response in animals anesthetized with pentobarbital. We conclude that pentobarbital inhibited TSH response to cold but did not reduce the resting levels. Ether inhibited the rise of TSH in the cold and lowered the basal levels of TSH in animlas at room temperature. Pentobarbital increased the response to TRH and ether may have reduced the response to TRH.     

The effects of sodium pentobarbital or ether anesthesia on spontaneous and electrochemically-induced gonadotropin release.

Studies were undertaken in the isolated blood perfused dog heart to determine the nature of the myocardial refractoriness induced by veratrum alkaloids. The initial intracoronary injection of cryptenamine acetates (Unitensin) was always associated with an increase in myocardial contractility and a loss of myocardial potassium. Subsequent doses produced refractoriness with respect to both the contractile and potassium responses. Acetylstrophanthidin still produced an inotropic and potassium losing effect duct of the glycoside was potentiated whereas the contractile response was not.     

Effects of short term experimental diabetes on brain serotonin metabolism

Serotonin metabolism was studied in several brain regions of control and Streptozotocin-treated male Wistar rats. After induction of diabetes, the animals were killed at 24 hours. Concentrations of brain tryptophan show a generalized increase in all brain regions, being only significant in medulla-pons. Serotonin levels do not change, while 5-HIAA concentrations, as well as the ratio 5-HIAA/5-HT, show significant increases in medulla-pons and mid-brain.     

Effects of pentobarbital anesthesia on the energy metabolism of murine tumors studied by in vivo 31P nuclear magnetic resonance spectroscopy

The effects of pentobarbital anesthesia on the energy metabolism of FSaII and MCaIV foot tumors in mice were studied by 31P MRS. Using an 8.5 T spectrometer, in vivo spectra were obtained in 15 animals before and after pentobarbital anesthesia (0.05 mg/g ip). The average phosphocreatine/inorganic phosphate ratios (PCr/Pi) with and without pentobarbital were similar for both tumor histologies. Effects on individual tumors, however, were greater than 20% in 9/15 animals and greater than 50% in 6/15 animals. Pentobarbital anesthesia increased the variability of tumor intracellular pH, and the phosphomonoester/nucleotide triphosphate (PME/NTP) and nucleotide triphosphate/inorganic phosphate ratios (NTP/Pi). When examining the average in a cohort, pentobarbital anesthesia had no significant effect on the PCr/Pi, PME/NTP, NTP/Pi ratios or the pH. However, approximately equal to 50% of individual tumors do have significant changes in these parameters. The anesthesia-induced variability of tumor energy metabolism may explain the decrease in TCD50 observed in previous studies using multifraction radiation.     

Effects of sodium pentobarbital anesthesia on blood flow in skin, myocutaneous, and fasciocutaneous flaps in swine.

Drug effect on flap blood flow is most commonly determined in anesthetized animals, yet the effect of the anesthetic is often poorly understood. Halothane and nitrous oxide cause profound changes in skin blood flow and thus provide an unsuitable anesthetic technique for use in measuring drug effects on skin and myocutaneous flaps in swine. The goal of this study was to determine the effects of sodium pentobarbital anesthesia on cardiovascular parameters and blood flow in skin, myocutaneous, and fasciocutaneous flaps in pigs. In seven pigs, 7 forelimb skin flaps, 7 forelimb fasciocutaneous flaps, 14 arterial buttock flaps, and 14 latissimus dorsi flaps were created. Blood flow was measured at 2-cm intervals along each flap while the animal was awake and anesthetized. A cardiac depressant effect of pentobarbital was observed, but no change in blood flow could be demonstrated in control skin or control muscle. However, pentobarbital did significantly increase blood flow in all viable portions of arterial and random skin flaps, fasciocutaneous flaps, and the cutaneous segments of the latissimus dorsi flap. These demonstrated effects of pentobarbital should be taken into consideration in designing and analyzing studies of flap blood flow in the acute postoperative phase.