Intravenous chloralose is a safe anesthetic for longitudinal use in beagle puppies

Chloralose is an intravenous anesthetic which preserves vagal and central baroreceptor reflexes, thus rendering it useful for physiologic research. However, chloralose is recommended for terminal experiments only, due to concerns relating to long-term toxicity. We investigated the safety of chloralose in longitudinal pulmonary function studies in beagle puppies. Twelve puppies received chloralose anesthesia repeatedly (8-12 times per dog) between the ages of 80 and 300 days. Constant anesthetic depth was maintained reliably throughout the course of the experiments. Recovery lasted approximately 4 hours in each experiment and occurred in four definable stages. Following recovery, the puppies exhibited normal health and growth as compared with other colony animals. There was no biochemical evidence of acute renal, hepatic, pancreatic or cardiac toxicity prior to and immediately after anesthesia, and no evidence of chronic toxicity following completion of the study protocol, after a total cumulative dose of 1.18 g/kg chloralose. These studies demonstrate that intravenous chloralose is a safe anesthetic for longitudinal use.     

A guinea pig cage for easy cleaning.

A simple cage and rack system was designed for holding guinea pigs in a laboratory environment. The shoe box solid floor cage, made of plastic, has 2 holes for "outside of cage" watering and "outside of cage" feeding. All of the accessory equipments such as automatic watering devices and feeders were set on rack shelves to design the cage simply. This system has satisfactorily functioned for about one year in our laboratory and has substantially saved labor in the washing process.     

A new anesthetic agent for use in the gerbil

Gerbils have been neglected in published reports on anesthesia. This study compared several dosages of Telazol used for anesthesia in the gerbil. Each group of animals injected with Telazol was evaluated for onset and duration of anesthesia and analgesia. Results showed Telazol to be a safe anesthetic and when dosed at 60 mg/kg to be suitable for major surgical procedures. Lower dosages of Telazol, in contrast, provided immobility and analgesia suitable for less nocioceptive and noninvasive experimental manipulations. Dosages of Telazol required for surgical depth of analgesia and anesthesia were accompanied by a prolonged recovery time. Gerbils should be monitored closely to insure a safe recovery when using the higher dosages.     

Altered NADH and improved function by anesthetic and ischemic preconditioning in guinea pig intact hearts

NADH increases during ischemia because O(2) shortage limits NADH oxidation at the electron transport chain. Ischemic (IPC) and anesthetic preconditioning (APC) attenuate cardiac reperfusion injury. We examined whether IPC and APC similarly alter NADH, i.e., mitochondrial metabolism. NADH fluorescence was measured at the left ventricular wall of 40 Langendorff-prepared guinea pig hearts. IPC was achieved by two 5-min periods of ischemia and APC by exposure to 0.5 or 1.3 mM sevoflurane for 15 min, each ending 30 min before 30 min of global ischemia. During ischemia, NADH initially increased in nonpreconditioned control hearts and then gradually declined below baseline levels. This increase in NADH was lower after APC but not after IPC. The subsequent decline was slower after IPC and APC. On reperfusion, NADH was less decreased after IPC or APC, mechanical and metabolic functions were improved, and infarct size was lower compared with controls. Our results indicate that IPC and APC cause distinctive changes in mitochondrial metabolism during ischemia and thus lead to improved function and tissue viability on reperfusion.     

Intravesical BCG administration in the guinea pig. A histomorphological study

Intravesical BCG administration is used as an adjuvant therapy after transurethral resection for superficial bladder cancer in man. The mechanisms of its antitumor activity are not known. The aim of this study was to characterize the histomorphological changes in various organs of the guinea pig after intravesical BCG administration. The BCG preparation used was BCG-RIVM, a Dutch BCG preparation. Instillations were performed in previously undamaged bladders weekly for 6 consecutive weeks and lasted 30 min or 1 h. Different doses were used ranging from 10(3) culturable particles (c.p.) to 5 x 10(7) c.p. of BCG. After 6 weeks, the animals were killed and postmortem examination was performed. The bladder wall, retroperitoneal lymph nodes, spleen, liver, lungs and distant lymph nodes were examined histologically. The BCG therapy, with a dose of 10(6) culturable particles and higher, induced an inflammatory reaction consisting of mononuclear infiltrates in the subepithelial tissue of the bladder wall. In approximately 50% of the animals investigated, the infiltrates were accompanied by non-caseating granulomatous lesions indicated by the presence of epithelioid cells. In general, the epithelial layer of the bladder showed no visible alterations. Similarly, a granulomatous inflammatory reaction was observed in the first retroperitoneal (iliac) lymph nodes draining the bladder. Granulomatous lesions were occasionally also present in liver and lung. In three of the 29 animals investigated, lesions were present both in liver and lungs, and in two of these three animals a granulomatous reaction was observed in the spleen and distant lymph nodes indicating a generalized inflammatory response induced by BCG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Monoamines and lordosis in the female guinea pig.

Serotonin and dopamine antagonists have been reported to induce lordosis in estrogen-primed spayed rats in the absence of progesterone. In the present study with guinea pigs, however, no such effect was found with any of the drugs tested, which include methysergide, parachlorophenylalanine (PCPA), haloperidol, and amphetamine. When given with progesterone, methysergide slightly decreased latency to heat, whereas PCPA substantially reduced lordotic response. Methysergide did not alter the inhibitory phase of progesterone action.     

A semiautomated procedure for rapid intrarectal instillation of fluids in the guinea pig.

A penumatic operated semiautomatic system was developed for the intrarectal instillation of solutions in the guinea pig. The apparatus permitted one person to inject large numbers of animals at considerable savings in time compared to manually operated syringe techniques. The procedure was shown to be both rapid and safe for administering solutions intrarectally in the guinea pig.     

Variation in guinea pig responsiveness.

Over the years, many reports have been published in which mention has been made of the variation in guinea pig responsiveness due to a number of different influences. In this review, we have attempted to summarize these findings with respect to genetic factors, age, sex, diet, season of the year, infection, and stress.     

Innovar-Vet-induced pathologic changes in the guinea pig.

High doses of Innovar-Vet administered im induced pathologic changes in tissues at the site of drug deposition. The onset and extent of the changes were dose related. Distal self-mutilation occurred coincidentally to the peak of pathologic changes in the ischiatic nerve.     

A homologous radioimmunoassay for guinea pig corticosteroid-binding globulin

A rapid, specific, and sensitive (requiring only 20 fmole of antigen equivalent to 0.007 microliter of serum) radioimmunoassay (RIA) was developed for the measurement of guinea pig corticosteroid-binding globulin (CBG). CBG was purified to homogeneity from guinea pig serum by affinity chromatography and used for immunization, as the standard and as the radiolabeled trace in the RIA. The antiserum to CBG was raised in rabbits. It was judged specific by immunoelectrophoresis and by comparison of RIA values with steroid-binding assay profiles obtained on serum separated on the basis of size and ion-exchange properties. The results of the radioimmunoassays agree with those of a steroid-binding assay run on identical samples. The sensitivity of the assay allows detection of CBG in serial serum samples, other biologic fluids such as milk, and cell culture supernatants.     

Sulfated glycosaminoglycans in guinea pig neutrophils studied by use of cationic colloidal gold.

Using a high electron resolution staining method, cationic colloidal gold (CCG, pH 1.0) staining, we studied the fine structural localization of sulfated glycosaminoglycans (GAGs) in various maturational stages of guinea pig neutrophils. Azurophil and specific granules of neutrophils reacted positively to CCG, with variety in labeling according to maturation. All immature azurophil and specific granules were labeled selectively. Mature granules lost their affinity with CCG. CCG-positive labeling was also observed in the trans to trans-most Golgi apparatus of promyelocytes and myelocytes. Prior absorption with poly-l-lysine prevented CCG labeling of tissue sections. Mild methylation of ultrathin sections at 37C did not alter CCG labeling, whereas CCG labeling disappeared after active methylation at 60C. Treatment with chondroitinase ABC or heparinase I abolished the majority of CCG labeling. These findings suggest the existence of sulfated GAGs not only in immature azurophil but also in immature specific granules of neutrophils. Sulfation of GAGs occurs in the trans- to trans-most Golgi apparatus of neutrophil granulocytes. A possible correlation between accumulation of sulfated GAGs and maturation of specific granules in neutrophils is also discussed.     

Estrogen sulfotransferase distribution in tissues of mouse and guinea pig: steroidal inhibition of the guinea pig enzyme.

The highest total activity of estrogen sulfotransferase in guinea pig is in liver and the highest specific activities are in the adrenal and the midgestational chorion. Guinea pig gonads contain scarcely detectable activities. In CD-1 mice the highest specific activity is in testis and the highest total activity is in late placenta. Adrenals from both sexes and ovaries contain minimal activities, while liver and fetal membrane activities are remarkably low. In CD-1, DBA, C57BL, and BALB mice, qualitative patterns are similar. Purified or partially purified estrogen sulfotransferase from guinea pig adrenal and chorion were used to study the effect of a number of possible steroidal inhibitors. Considerable structural specificity is evident within a range of steroids, even among some which are not substrates. Pregnenolone is the most effective 21-carbon inhibitor and, in general, more highly hydroxylated forms are less inhibitory. Within a series of 21-, 19- and 18-carbon steroids, the structure of the A ring appears to be extremely important in regard to inhibitory effects.     

A novel radioimmunoassay for neuromedin K. I. Absence of neuromedin K-like immunoreactivity in guinea pig ileum and urinary bladder. II. Heterogeneity of tachykinins in guinea pig tissues

A novel and highly specific radioimmunoassay for the tachykinin peptide neuromedin K (NMK, also known as neurokinin beta, neurokinin B) has been developed and used to determine the distribution of this peptide in extracts of guinea pig tissues. In addition to immunoreactive components coeluting with the 3 mammalian tachykinins, substance P (SP), substance K (SK) and NMK, analyses using reverse-phase HPLC revealed immunoreactive peaks coeluting with the C-terminal octapeptide of SK (SK-(3-10], an N-terminally extended form of SK (gamma-preprotachykinin-(72-92)amide), and a yet unidentified peak eluting before NMK in the extracts of guinea pig brain and spinal cord. In contrast to the other tachykinins, SP and SK, which were present in high concentrations in extracts of all peripheral and central tissues examined, NMK-like immunoreactivity was detected only in extracts of central tissues. NMK-like immunoreactivity was not detected in extracts of terminal ileum and urinary bladder.     

Evidence for A1 and A2 adenosine receptors in guinea pig trachea

The adenosine analogs [5'-N-ethylcarboxamideadenosine (NECA), 2-Chloro-adenosine (2-ClA), R-phenylisopropyladenosine (R-PIA), N6-cyclohexyl adenosine (CHA), and N6-cyclopentyladenosine (CPA)] produced both relaxation and contraction responses in isolated guinea-pig trachea. A concentration-related relaxation response was observed in trachea which were precontracted with either histamine or KC1. This response followed an order of analog potency that was indicative of the A2 receptor subtype (NECA greater than 2-ClA greater than R-PIA greater than CPA greater than CHA). Theophylline, an adenosine-receptor antagonist, blocked this relaxation response. In addition, a concentration-related contractile response was produced with adenosine analogs in those trachea that were not previously contracted. In contrast, the contractile response followed an analog potency indicative of the A1 receptor subtype (R-PIA greater than 2-ClA = CPA = CHA). This contractile response was not mediated by cholinergic, adrenergic or histaminergic receptors. 2-ClA induced a biphasic response, while NECA only relaxed these tissue under basal tone. Unlike the relaxation response, these contractile responses were not attenuated by theophylline, but were blocked by 1,3 dipropyl-8-(2 amino-4-chlorophenyl)xanthine (PACPX). These findings confirm the existence of two subpopulations of adenosine receptors in guinea pig trachealis muscle.