Starting your day off with some cute before we get down to brass taxes.
Differential neural activation of vascular α-adrenoceptors in oral tissues of cats.
Author: Michael C Koss
*Available on PubMed, here*
Objectives:
Previous studies had determined that
α-adrenoreceptors play a part in vascular constriction of the gingiva.
The goal
of this paper was to determine the contribution of two subtype adrenoreceptors
(α1 and α2) involved in vasoconstrictor responses in gingiva tissues in anesthetized cats.
They did this by electrically stimulating the cervical sympathetic nerve to create vasoconstriction responses, and subsequently administered drugs specifically designed to act on α1 and/or α2-adrenoreceptors.
By measuring blood flow at three sites; gingiva, lingual artery & tongue, they can identify the degree of vasoconstriction, and depending on which drugs create an antagonistic effect, they will know which subtype adrenoeceptor is mediating the response.
Results:
1. Electrical stimulation of the cervical
sympathetic nerve resulted in a decrease of blood flow at
all three sites (Gingiva, Lingual Artery & Tongue).
The depressions of this graph identify vasoconstrictor responses immediately after electrical stimulation. Vasocontriction occurs at all three locations; tongue, lingual artery & gingiva.
This graph shows that as Frequency of the stimulation increases the % Vasoconstriction of all three sites increases.
2. All three responses were equally antagonized (or inhibited) by administration of the drug "Phentolamine". This drug is a non-selective α-adrenoreceptor antagonist, therefore it would act on all α-adrenoreceptors.
It can be seen here, as "Phentolamine" is added in increasing doses the % Vasoconstriction of all three sites is decreasing significantly (*). Which means this drug is antagonizing, or inhibiting, the vasoconstriction responses.
3. The drug "Prazosin" is a specific antagonist for α1-adrenoceptor. Administration of this drug reduced vasoconstriction in the lingual artery and gingiva,
but not in the tongue. Subsequent
administration of "Rauwolscine" (a specific antagonist for α2-adrenoceptors) antagonized vasoconstriction of all three locations.
Similar to Fig. #1, the depressions of this graph indicate vasoconstrictory responses. It can be seen that after the addition of the drug "Prazosin" the tongue still experiences vasoconstriction, but the lingual artery does not. After the addition of "Rauwolscine", both responses are inhibited.
A bar graph to represent the significance of Fig. #4.
4. However, when given alone, "Rauwolscine" blocked vasoconstriction in the tongue only, with no effect on gingival or
lingual artery vasoconstriction. Subsequent administration of "Prazosin" largely antagonized the remaining vasoconstriction responses.
When drugs are reversed, "Rauwolscine" only elicits an antagonistic effect on the tongue. While "Prazosin" inhibits the vasoconstriction response in all three locations.
5. In the cat's oral cavity, it appears that the neural vasoconstrictor responses of the gingiva and lingual artery are mediated by both α1- and α2-adrenoceptors. Whereas, tongue surface vasoconstrictor
responses seem to be mediated primarily
by α2-adrenoceptors.
My Critique:
This paper was useful and easy to follow. It got to the point quickly without using too much jargon. That being said they didn't use a lot of background information. I needed to look up these drugs individually myself to learn their uses and functions. They also don't explain the different between alpha-1 & alpha-2 adrenoreceptors. I believe this paper was written for an audience with previous knowledge of the drugs used, physiology, and biochemistry, so this information that I say is missing may have been implied.
I find the results strongly support the authors' claims. The experiment is straight forward and well conducted and they have numerous other studies that back up their findings in other species. They do state in the discussion that there are things that can alter results, such as degree of anesthesia and methodologies for measuring blood flow.
The figures had detailed legends and titles which made them easy to understand and follow. They directly corresponded to the results and discussion ad didn't take long to figure out. The methodology seemed sound and the results were well organized. Overall, a very good paper.
This paper was useful and easy to follow. It got to the point quickly without using too much jargon. That being said they didn't use a lot of background information. I needed to look up these drugs individually myself to learn their uses and functions. They also don't explain the different between alpha-1 & alpha-2 adrenoreceptors. I believe this paper was written for an audience with previous knowledge of the drugs used, physiology, and biochemistry, so this information that I say is missing may have been implied.
I find the results strongly support the authors' claims. The experiment is straight forward and well conducted and they have numerous other studies that back up their findings in other species. They do state in the discussion that there are things that can alter results, such as degree of anesthesia and methodologies for measuring blood flow.
The figures had detailed legends and titles which made them easy to understand and follow. They directly corresponded to the results and discussion ad didn't take long to figure out. The methodology seemed sound and the results were well organized. Overall, a very good paper.
Paper Reference: Koss, Michael C. (2002). Differential neural activation of vascular α-adrenoceptors in oral tissues of cats. European Journal of Pharmacology, 440: 53– 59.
That's it! Now, back to cute...
Awwwww....
Enjoy this cat video, it doesn't really have anything to do with tongues, but it's hilarious.
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