摘要:

AbstractThe effect of strychnine was studied on the slow, fast, and inhibitory systems in the abdominal extensor muscles of the crayfish. Strychnine nitrate (0.1 mg/ml and up) caused rapid block of the fast responses of the deep abdominal extensor muscles. The nerve and muscle remained directly excitable, and the blocked preparation contracted with added glutamate. It is concluded that strychnine acts mainly presynaptically or to neutralize the transmitter substance. No marked effect was observed on the purely slow superficial extensor muscles or on inhibitory systems. Essentially the same results were obtained in other slow and fast systems ofPachygrapsusandPanulirus. The possibility of a common transmitter substance for the slow and fast neuromuscular systems is discussed.

ISSN:0021-9541    

DOI:10.1002/jcp.1040680102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractIn dermal melanocytes ofRana pipiens, colchicine is known to produce a gradual, dosage‐dependent dispersion of melanin granules, irreversible over several hours. This effect is potentiated by a number of chemical agents that normally produce a reversible dispersion of granules. In the present study we examined the effect of high hydrostatic pressure on changes induced in melanocytes by colchicine.In Ringer's solution, samples of skin from a single frog were incubated for 30 minutes at room temperature with or without colchicine, 9 × 10−5M. Then two samples, one of which had been pretreated with colchicine, were successively subjected to 12,000 psi for one hour at 25 to 26°C. The degree of dispersion of melanin granules in melanocytes was observed before, during and after the period of pressure.In frog skin pretreated with colchicine, the usually gradual, irreversible dispersion of melanin granules in melanocytes was potentiated.Since high pressure is known to produce solational changes in protoplasm, such changes may accompany dispersion of melanin granules in melanocytes. If this be so, then sol‐gel equilibria may be important in the action of dispersing and aggregating agents, many of which are hormones and other physiologically active agents. Finally, the present study supports the hypothesis that colchicine shifts protoplasmic sol‐gel equilibria toward a less gelated

ISSN:0021-9541    

DOI:10.1002/jcp.1040680103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe effect of ammonium chloride on the cellular Na+, K+and water has been examined in human and horse (high K), cow (medium K) and cat (low K) red cells. It was found that high K red cells, especially those of the horse, gained water an Na+, whereas the net movement of K+was negligible. There was a correlation between the increase of cellular Na+concentration and of the packed red cell volume. In contrast, the packed cell volume of low K red cells increased slightly or not at all, and Na+ions leaked out from the cells. The high K cells had a lower Cl−concentration and higher buffer capacity than the low K cells. The results obtained with the medium K (cow) cells usually lay between those of the other two cell types. In all the cases both the plasma and cell pH decreased resulting from the addition of ammonium chloride. The mechanism of movements of water and Na+ions in high K cells remained unsolved, but the response of low K cells to ammonium chloride was near that of a cation exchange resi

ISSN:0021-9541    

DOI:10.1002/jcp.1040680104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe amounts of 5‐hydroxytryptamine (5‐HT) in the skin of nine species of anurans were estimated by the fluorescence method. Relatively large quantities of 5‐HT were found in the dorsal skin of five species of semi‐terrestrial frogs, while in the skins of four highly aquatic species none, or only a trace, was found. Using the histochemical fluorescence method of Falck, 5‐HT was located in the granules of the venom glands ofRana pipiens, a semi‐terrestrial species, while no fluorescing glands were found inR. catesbeiana, a highly aquatic species. The results of Erspamer and others are discussed. It is suggested that the most probable role of 5‐HT in frog skin is that of defense against l

ISSN:0021-9541    

DOI:10.1002/jcp.1040680105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractUsing paired frog muscles it was shown that fluoride caused no observable change in the rate of oxygen consumption in Ca++‐free Ringer's solution, but stimulated the rate in Ca++‐containing Ringer's; the obvious explanation for this stimulation is the spontaneous activity of the muscle caused by the rapid lowering of Ca++ion concentration when fluoride was added. Fluoride had no effect on potassium movement in these experiments. In a Ca++‐free solution fluoride (0.03 M) inhibited the insulin + lactate‐stimulated oxygen consumption of muscles which had been adapted to the absence of calcium by overnight soaking. In Ca++‐containing Ringer's there was no net effect of fluoride, demonstrating the fact that the direct inhibition of oxygen consumption was cancelled by the indirect stimulation caused by the fluoride‐lowering of the Ca++ion concentration. Fluoride depressed the IL‐induced K uptake but for this effect some calcium, albeit a very low concentration, was necessary. Fluoride did not alter the muscle glycogen concentrations.The only observable effect of calcium (in the absence of fluoride) was a rise in respiration caused by exposure to a sudden reduction in Ca++ion concentration. Both the IL‐stimulated O2rate and K uptake were independent of Ca++ions since they occurred in Ca++‐free adapted muscles, in muscles exposed to a rapid reduction of Ca++ions as well as in muscles in a Ca++‐containin

ISSN:0021-9541    

DOI:10.1002/jcp.1040680106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractElectrical activity in response to light stimuli was recorded from the brain of the cricket (Gryllus domesticus) using stainless steel microelectrodes. Four basic types of elements were observed as follows: (1) units which registered ambient light intensity by frequency of firing as well as responding with transient changes in rate to stepwise increases or decreases in intensity; (2) units which fired at a higher frequency in dark than in light; (3) units which fired continuously at low level in light and responded with a transient high frequency burst to light off; and (4) units which responded with a brief burst to on and off, but tended to be “on‐dominant” or “off‐dominant.” Also observed were synchronized spikes in mushroom body responding primarily to light off, but also on occasion to light on, and often accompanied by single unit responses. The units registering intensity are probably homologous with units showing similar properties recorded from the visual systems of several other arthropods and usually referred to as “sustaining units.” On‐off, off, and dark units are also known from other forms. The mushroom body light responses were similar to synchronized spikes recorded in cockroach mushroom body following ant

ISSN:0021-9541    

DOI:10.1002/jcp.1040680107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractIt is possible to use the purine pyrophosphorylase in mammalian cell culture systems as a genetic marker in selecting small numbers of enzyme positive cells from large populations of pyrophosphorylase negative cells of the mouse lymphoma line P388 in medium containing amethopterin, hypoxanthine, glycine and thymidine. Conversely, it is readily possible to obtain pyrophosphorylase‐deficient cells by treatment with 8‐Azaguanine. We were unsuccessful in demonstrating DNA‐mediated transformation using DNA from enzyme positive cells incubated with cells which were enzyme neg

ISSN:0021-9541    

DOI:10.1002/jcp.1040680108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe effects of three physical‐chemical factors, temperature, hydrogen ion concentration, and partial pressure of oxygen, on the respiratory functions of blood of the toad (Bufo marinus) have been studied.Measurements of oxygen affinity of hemoglobin in whole blood were measured tonometrically by a method devised for small quantities of blood. At pH 7.40 and 25°C blood was found to be 50% saturated with oxygen at a partial pressure of 44 mm Hg of oxygen. The Bohr effect was measured at various temperatures and found to be about one‐half that found for mammalian blood. Carbon dioxide content of toad blood changes only slightly in the oxygenated and reduced states. Thus the “Haldane” effect parallels the small Bohr effect. Toad blood was found to have average hematocrit values of 37% for erythrocytes and average hemoglobin values of 11 gm/100 ml per cubic millimeter of blood. The respiratory functions of the blood of the toad conform to the pattern of respiratory mechanisms available for gas exchange between the environment and tissues of the

ISSN:0021-9541    

DOI:10.1002/jcp.1040680109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe electrophoretic mobilities of Ehrlich ascites, sarcoma 37 ascites, mouse liver cells and their isolated nuclei were measured under similar environmental conditions. No differences in mobility were detected between cells and homologous nuclei from the same cell population and it was concluded that their surface charge densities were probably the same. The effect of neuraminidase on Ehrlich ascites and liver cells and nuclei was also determined; neuraminidase reduced the mobility of Ehrlich ascites cell nuclei as well as cells. The reduction in mobility of cells and nuclei prepared by a sucrose method was the same; however, the reduction in mobility of citric acid prepared nuclei was less than that of citric acid treated cells. The reduction in mobility of both liver cells and nuclei was small or insignificant. It is suggested that although cells and nuclei have similar electrophoretic mobilities, possibly different groups contribute to their surface charge.

ISSN:0021-9541    

DOI:10.1002/jcp.1040680110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe ability of neutrophil leukocytes to extravasate into the peritoneal cavity in response to an intraperitoneal injection of bacterial endotoxin was studied in mice. The normal response of a marked accumulation of intraperitoneal neutrophils was completely abolished by halothane anesthesia. It was further shown that such abolition depended upon the presence of halothane duringthe time the extravasation would normally be occurring. The evidence points toward an effect on either the leukocyte or the vessel rather than a non‐specific “stress” effect. It is suggested that the effect is on the neutrophil, rendering it less deformable and, hence, less able to undergo trans‐vascular dia

ISSN:0021-9541    

DOI:10.1002/jcp.1040680111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY