Rabbits insulin release

Fig. 2u Insulin secretion in vitro". Insulin release from pieces of rabbit pancreas effected by glucose before and after addition of guinea pig antiinsulin serum. Note complete inhibition of I LA by anti bodies.

Fig. 5 shows the response of the pancreatic slices of rats, rabbits, dogs and calves to glucose stimulation, respectively. The absolute amount of insulin released increased according to the absolute rate of basic insulin secretion, which in turn, correlated well with the quantity of extractable insulin determined in the pancreatic glands of the different species. Pancreatic insulin contents amounted to 0.7 - 1.0 U insulin/g pancreatic tissue in rats,... 

U/g in rabbits, 2-8 U/g in calves (regarding calves s.also Pfeiffer etal (1957)). On the other hand, the relative increases in insulin released following stimulation were independent from both, basic insulin secretion and extractable pancreatic insulin content. The ratio secretion rate following stimulation to basic secretion rate amounted to 5tl for rabbits and 3 1 for dogs and calves, the absolute loss in extractable pancreatic insulin content not... 

Finally, serotonin was also shown to effect insulin release from the rabbit pancreas in the "in vitro" preparation (Fig.14), whereas "in vivo" neither in animals nor in men did stimulation of insulin secretion occur. However, with the exception of this... 

Fig. 15. Insulin secretion in vitro" Insulin release from pieces of rat and rabbit pancreas, respectively, effected by Hb 419 and Tolbutamide in different concentrations. Note the approximately 100 and 1000 times more effective actions of Hb 419 on rat and rabbit pancreas, respectively.

Somatostatin. Somatostatin is an endogenous peptide hormone involved in e.g. the control of the release of Somatomedin, Insulin and Pancreatin. Due to its biological role, Somatostatin has a very low biological stability. The half-life in the rabbit after intravenous administration has been determined to approximately 90 seconds in this investigation. After sc or im administration, the apparent half-life is somewhat longer, close to 10 minutes, probably due to the absorption of the peptide from the injection site into the systemic circulation. 

Callens, C., and Remon, J. P. (2000), Evaluation of starch-maltodextrin-Carbopol 974 P mixtures for the nasal delivery of insulin in rabbits, J. Controlled Release, 66, 215-220. 

The combined effect of (3-CyD with absorption enhancers such as sodium glycocholate or Azone on the nasal absorption of human fibroblast interferon- 3 in powder form in rabbits has been described. HP- 3-CyD was useful as a biocompatible solubilizer for lipophilic absorption enhancers involved in the nasal preparations of peptides.When insuUn was admiifistered nasally to rats, simultaneous use of an oily penetration enhancer, HPE-101, (l-[2-(decylthio)-ethyl]azacyclopentane-2-one) or oleic acid solubilized in HP-(3-CyD showed a marked increase in serum immuno-reactive insulin levels and marked hypoglycemic (Figure 40.11). The potentiation of the enhancing effect of HPE-101 by HP-(3-CyD can be explained by the facilitated transfer of HPE-101 into the nasal mucosa. Studies on the release of membrane proteins and scanifing electron microscopic observations of rat nasal mucosa indicated that the local mucosal damage due to the combination with HP- 3-CyD may not be serious obstacles to their safe use. 

Medication can be delivered via the eye in the form of eyedrops or in an ocular device. Sodium or zinc insulin was incorporated into a Gelfoam sponge-based device. An in vitro dissolution test indicated that the release of insulin from the device was proportional to the flow rate of the dissolution medium. An in vivo dissolution experiment provided support for the hypothesis that there was a direct relationship between the prolonged pharmacological response to insulin and its release from the device. The ocular device with or without the aid of an enhancer was placed in the eye of rabbits as an ocular insert and produced a uniform blood glucose-lowering effect of 60% over 8h. The blood glucose... 

PEGylated chitosan nanoparticles were shown to enhance insulin absorption to a greater extent compared with non-nanoparticulate forms of chitosan and insulin alone. Chitosan nanoparticles were also found to enhance nasal absorption of insulin in rabbit, regardless of chitosan molecular weight. Recently, Al-Qadi and co-workers reported that intratracheal administration of diy insulin powder microencapsulated in chitosan nanoparticles increased its distribution to the deep lungs, and facilitated release of a biologically active form of insulin to rat blood. Moreover, they observed a more pronounced and prolonged effect compared to non-formulated insulin. ... 

Fig. 7. Insulin secretion in vitro The effect of leucine on the release of insulin from pieces of rabbit and rat pancreas.

Gastrin-pentapeptide from Imperial Chemical Industries, England, though somewhat less potent clearly induced release of insulin by the rabbit pancreas "in vitro", too (Fig.13). Wore details on the insulin stimulating action of these intestinal hormones are given elsewhere (Schroder et al (1967)). 

Fig. 14. Intestinal Hormones Affecting Insulin Secretion in Vitro Serotonin 10-200 y/ml. Release of Insulin from Rabbit ancreas.

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