A comparative study of guinea pig and rat tracheal reactivity

Species differences in behavior and responses of guinea pig (GPT) and rat (RT) tracheal smooth muscle to electrical field stimulation (EFS) and chemicals were investigated under semi-isometric conditions. Indomethacin augmented and papaverine reduced the contractions elicited by EFS in both tissues. They relaxed the GPT and did not affect the tone decline in the RT. Experiments with different load, cartilage content, thread and rubber strips suggest the role of elastic elements in passive elongation of the RT. This was independent of muscarinic, adrenergic, histaminergic and serotoninergic receptors, nitric oxide, eicosanoids and metabolic processes. The second response on repeated administration of acetylcholine was augmented and that of serotonin attenuated in both GPT and RT. Upon repeated elevation of [K+]o the tissues responded in an opposite manner. Further data are provided on similarities (modulation of cholinergic transmission by prostaglandins, sensitization to acetylcholine and desensitization to serotonin) and differences (innervation, responses to repeated elevation of [K+]o, presence/absence of prostaglandin-regulated basal tone and spontaneous activity) in reactivity of GPT and RT.     

Nonuniform biosynthesis of multiple hemoglobins in the adult rat and guinea pig

Separation of adult rat bone marrow cells by the method of thin layer countercurrent distribution permits the analyses of 59Fe-tagged erythroid cells for the various multiple hemoglobins and the assignment of such hemoglobins to erythroid cells at different stages of their development. Of the six adult red cell hemoglobins, hemoglobin 5 is synthesized most actively in the earliest erythroid cell whereas hemoglobin 4 (the major hemoglobin of the red cell) is synthesized most actively in the latest erythroid cells, e.g. the reticulocyte. Experimental evidence also indicates that maturation of the erythroid cell is accompanied by a decreased rate of synthesis of hemoglobin 5. The earliest erythroid cells of the marrow contain two hemoglobins, 7 and 8, which are absent in the adult red cell. Similar studies with the guinea pig confirm the nonuniform biosynthesis of its two hemoglobins and suggest that the phenomenon may be a general one among mammalian multiple hemoglobins.     

The effect of halofenate or halofenate free acid on human, rat and guinea pig platelet aggregation

Halofenate free acid (HFA), the major metabolite of the hypolipemic agent halofenate, blocked the secondary phase of human platelet aggregation induced by ADP, epinephrine, or thrombin; higher concentrations of clofibrate free acid (CFA) were required to produce similar inhibitory effects on platelet aggregation. HFA and CFA inhibited collagen-induced aggregation of human, rat, or guinea pig platelets. Halofenate orally administered to rats caused inhibition of collagen-induced aggregation when plasma levels of HFA exceeded 300 mug/ml, a clinically achievable human plasma concentration. The platelet inhibitory effects of clofibrate administration were less than those observed with halofenate administration.     

The response of primary horizontal semicircular canal neurons in the rat and guinea pig to angular acceleration

In rats and guinea pigs, primary afferent neurons from the horizontal semicircular canal were divided into two categories, regular and irregular, on the basis of the regularity of their resting activity. Regular neurons tend to have higher average resting rates than irregular neurons and in response to a constant angular acceleration stimulus of 16.7 deg/s2 regular neurons tended to have lower sensitivity and longer time constants than irregular cells. Some irregular neurons are more sensitive to incremental accelerations than to decremental accelerations of the same magnitude, whereas regular neurons tend to show symmetrical sensitivity. In response to sinusoidal angular acceleration stimuli (fixed frequencies) in the range 0.01-1.5 Hz, cells which fired regularly at rest tended to have smaller gain and longer phase lag re acceleration at most frequencies than irregular cells. Transfer functions were obtained for averaged data for regular and irregular neurons separately in both species. In both species there is evidence of systematic variation between neurons within each category, and this systematic variation is obscured by averaging across neurons.     

Ontogeny of spontaneous locomotor activity in rabbit, rat, and guinea pig.

Investigated postnatal locomotor activity in 3 experiments with 43 New Zealand white rabbits, 20 Sprague-Dawley albino rats, and 11 Dunkin-Hartley albino guinea pigs. A peak was found in this behavior at 5 days of age in the rabbit and, in confirmation of earlier studies, at 15-20 days in the rat. Neonatal guinea pigs showed no variation in activity levels due to age. The guinea pig is born at an advanced stage of neural maturation in comparison with the rat, and the rabbit is born at an intermediate stage. This difference accounts for the observed variations in postnatal activity profiles if it is assumed that the behavioral peak coincides with the transition from a stage of primarily mesencephalic arousal system maturation to a stage of primarily diencephalic and telencephalic inhibitory system maturation. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensory innervation of the digital, palmar and plantar pads of the rat and guinea pig

The Authors have studied, with Ruffini's gold-chloride method, the sensitive innervation of the digital, metacarpal and metatarsal pads of the rat and guinea-pig. Nervous capsulated expansions and free terminations are described in this district.     

Noradrenaline-H3 uptake by isolated rat organs with active and blockaded adrenoreceptors

The beta-adrenoreceptor blocking agent propranolol was shown to activate noradrenaline-N3 absorption by the rat isolated organs by 30-180%. The alpha-adrenoreceptor blocking agent phentolamine only activated by 30-55% the noradrenaline-N3 absorption in the organs possessing the postsynaptic alpha-adrenoreceptors (ductus semen, spleen and amsll intestine). The beta-adrenoreceptor activator isopropylnoradrenaline decreased the intensity of noradrenaline-N3 absorption in all the organs by 15-50%. The alpha-adrenoreceptor activating agents (urine and mesaton) only depressed the noradrenaline-N3 absorption by 20-45% in the organs possessing postsynaptic alpha-adrenoreceptors. The data obtained suggest existence of reverse transsynaptic regulatory effects via adrenoreceptors of the cell-effector on the processes of noradrenaline absorption by adrenergic neuron.     

Stereoselectivity of the aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid in rat and guinea pig

Following administration of 6-n-propylchromone-2-carboxylic acid (6-n-PCCA) (500 mumol/kg) to male rats, three metabolic products were detected and isolated from the 0-24 h urine. All were identified as resulting from oxidation exclusively along the 6-n-propyl moiety. Some 66% of the dose was excreted in the 0-24 h urine, 55% of which was 6-PCCA, with 15% as (6-1'-hydroxypropyl)chromone-2-carboxylic acid (6-1'-HPCCA), 22% as 6-(2'-hydroxypropyl)chromone-2-carboxylic acid (6-2'-HPCCA), and 4% as 6-3'-carboxypropyl)chromone-2-carboxylic acid (6-3'-CPCCA). Derivatization of the methyl esters of the hydroxylated metabolites with S-alpha-methoxy-alpha-(trifuloromethyl)-phenylacetyl chloride (Mosher's reagent) allowed the evaluation of urinary enantiomeric composition by HPLC and assignment of their absolute configurations by NMR. This was found to be 90:10 (R/S) for 6-2'-HPCCA, and 7:93 (R/S) for 6-1'-HPCCA. When rats were dosed with the racemic 1'- and 2-hydroxy metabolites; no stereoselective metabolism or excretion was observed. Administration of 6-n-PCCA to male guinea pigs revealed that this species was unable to metabolise this compound.     

The intermolecular cross-links in uterine collagens of guinea pig, pig, cow, and human beings

The intermolecular cross-links have been studied in the uterine insoluble collagen of guinea pig, pig, cow, and human beings with a single given procedure. After NaB3H4 reduction, there are three intermolecular cross-links; namely, dihydroxylysinonorleucine, hydroxylysinonorleucine, and histidinohydroxymerodesmosine. In human uterine collagen samples these reduced cross-links are present in equal amounts. The reduced intermolecular collagen cross-links of uterine leiomyoma are very similar to those of the normal uterine tissue. Dihydroxylysinonorleucine is the principal reduced cross-link in uterine collagen of guinea pig, pig, and cow. Alkaline hydrolysis reveals that dehydrodihydroxylysinonorleucine and dehydrohydroxylysinonorleucine occur in vivo as glycosylated derivatives.     

Circularization and cleavage of guinea pig cytomegalovirus genomes

The mechanisms by which herpesvirus genome ends are fused to form circles after infection and are re-formed by cleavage from concatemeric DNA are unknown. We used the simple structure of guinea pig cytomegalovirus genomes, which have either one repeated DNA sequence at each end or one repeat at one end and no repeat at the other, to study these mechanisms. In circular DNA, two restriction fragments contained fused terminal sequences and had sizes consistent with the presence of single or double terminal repeats. This result implies a simple ligation of genomic ends and shows that circularization does not occur by annealing of single-stranded terminal repeats formed by exonuclease digestion. Cleavage to form the two genome types occurred at two sites, and homologies between these sites identified two potential cis elements that may be necessary for cleavage. One element coincided with the A-rich region of a pac2 sequence and had 9 of 11 bases identical between the two sites. The second element had six bases identical at both sites, in each case 7 bp from the termini. To confirm the presence of cis cleavage elements, a recombinant virus in which foreign sequences displaced the 6- and 11-bp elements 1 kb from the cleavage point was constructed. Cleavage at the disrupted site did not occur. In a second recombinant virus, restoration of 64 bases containing the 6- and 11-bp elements to the disrupted cleavage site restored cleavage. Therefore, cis cleavage elements exist within this 64-base region, and sequence conservation suggests that they are the 6- and 11-bp elements.     

Role of nitric oxide in responses to renin-angiotensin system inhibition in sodium-depleted guinea pig and rat

Previous reports have suggested that NO is an important mediator of the antihypertensive effects of renin-angiotensin system (RAS) inhibition. We examined the effects of the NO synthase inhibitor L-NNA on the hypotensive effects of captopril, the Ang II antagonist EXP 3174, or the renin inhibitor terlakiren. In sodium-depleted guinea pigs (GPs), L-NNA (3 mg/kg) increased MAP by 15-21% for at least 5 hours. L-NNA partially blocked the hypotensive effects of captopril (1 mg/kg, iv), but not those of EXP 3174 (1 mg/kg, iv) or terlakiren (3 mg/kg). In sodium-depleted rats, 10 mg/kg L-NNA (iv) increased MAP by 16-22%, and partially or fully blocked the hypotensive effect of EXP 3174 (1 mg/kg, iv) or captopril (3 mg/kg, iv), respectively. Thus, in contrast to the rat, NO in GPs appears to participate only in the hypotensive action of ACE inhibition and does not appear to be strongly involved in the hypotensive action of AII antagonism or renin inhibition. The involvement of NO in the hypotensive effects of RAS antagonists other than ACE inhibitors may be species-dependent.     

Skin surface lipids of the guinea pig

Skin surface lipids of the guinea pig were found to contain sterol esters (33%), wax diesters (diacyl alkanediols) (24%), glycerol ether diesters (28%), free fatty alcohols (6%) and free sterols (9%). The sterol esters and diacyl alkanediols contained saturated fatty acids (40 and 67%, respectively) having straight and singly-branched chains and mono-unsaturated acids (60 and 33%,respectively) derived predominantly by delta 9-desaturation of C15 and C16 straight-chain saturated fatty-acid precursors. The 1-O-alkylglycerols and fatty acids from the glycerol ether diesters were both entirely saturated series containing straight, branched and multi-branched chains. Both the free and the esterified sterols consisted principally of cholesterol with a small proportion of lathosterol.     

Desulphation of heparin by mice and guinea pig leukocytes

A series of 603 patients referred with atypical Papanicolaou smears was evaluated by repeat smears, colposcopically directed cervical biopsies, and endocervical curettage. These techniques as a unit can establish an accurate outpatient diagnosis superior to any of these modalities used alone and comparable with findings in conization and hysterectomy specimens. Endocervical curettage has made a unique contribution to the evaluation of such patients; these curettings have allowed examination of tissue fragments and are more reliable in diagnosing neoplasia than are endocervical smears. Invasive carcinoma and its precursors confined to the anatomic endocervical canal can be recognized by this technique, and conversely the absence of neoplastic epithelium in adequate endocervical curettings rules out occult carcinoma. Indications for conization of the cervix are discussed in reference to the other biopsy and cytologic findings, and guidelines are presented for patient management, stressing clinicopathologic correlation and cooperation.