Rectal compartment

Nishihata, T., and T. Higuchi. 1984. Promoting effect of concanavalin A on transport of sodium cefoxitin and phenol red from rat rectal compartment. Life Sci 34 419. 

The pH of the rectal compartment is essentially neutral, ranging from 7 to 8, with minimal buffering capacity as compared to the small intestinal milieu. Suppositories or solutions formulated to maintain a... 

This model is representative for the conditions described in the previous section, except for the mode of administration which can be oral, rectal or parenteral by means of injection into muscle, fat, under the skin, etc. (Fig. 39.7). In addition to the central plasma compartment, the model involves an absorption compartment to which the drug is rapidly delivered. This may be to the gut in the case of tablets, syrups and suppositories or into adipose, muscle or skin tissues in the case of injections. The transport from the absorption site to the central compartment is assumed to be one-way and governed by the transfer constant (Fig. 39.7a). The linear differential model for this problem can be defined in the following way ... 

Lorazepam is less lipophilic than diazepam and there is evidence that it has a longer duration of anticonvulsant action than diazepam after intravenous administration. This could be due to the fact that diazepam is more rapidly removed from the brain compartment than lorazepam, which limits its duration of antiepileptic activity. In practice, when diazepam is used to control status epilepticus it is often necessary to continue treatment with diphenylhydantoin, which has a longer duration of action in the brain. The principal hazards of benzodiazepines when given intravenously include respiratory depression and hypotension. Diazepam may be administered rectally, its ease of absorption leading to peak plasma levels within about 10 minutes. 

The metabolic clearance rate of PSA follows a two-compartment model with initial half-lives of 1.2 and 0.75 hours for free PSA and total PSA and subsequent half-lives of 22 and 33 hours. Because of this relatively long half-life, 2 to 3 weeks may be necessary for the serum PSA to return to baseline levels after certain procedures, including transrectal biopsy, transrectal ultrasonography, transurethral resection of the prostate, and radical prostatectomy. Prostatitis and acute urinary retention can also elevate PSA concentration. Although the digital rectal examination has no clinically important effects on serum PSA levels in most patients, in some it may lead to a twofold elevation. 

Our option Compartment filled by the rectal adventitia including nerves, vessels, lymph nodes... 

Our option Outer connective tissue lamella of the rectal adventitia, bordering the perirectal compartment... 

What is situated outside the rectal fascia and therefore outside the perirectal subcompartment Dorsally, the presacral subcompartment is loosely attached to the perirectal compartment (see above). Laterally the supplying structures (autonomic nerves and branches of the iliac vessels) of the urogenital organs constitute a nerve-vessel plate (Fig. 1.3c). The latter is accompanied by connective tissue and fills the remaining space between the perirectal compartment... 

Dorsomedially,the middle compartment abuts the posterior compartment. The border between these compartments is demarcated by the rectovaginal fascia/septum (see also Sect 1.3.1), that is composed of dense coimective tissue, elastic fibers [44] and smooth muscle cells that belong to the longitudinal layer of the rectal wall. 

Often an organ descent in/of the anterior or middle compartment typically leads to a compression of the ventral rectal wall. This finding can promote an internal rectal prolapse and might account for a stool entrapment and a stool outlet obstruction (Fig. 13.1c). 

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