Retrograde cannulation of femoral artery: A novel experimental design for precise elicitation of vasosensory reflexes in anesthetized rats

Abstract

Vasosensory reflex responses are elicited by instillation of nociceptive agents in a segment of peripheral blood vessel. A novel method for the stimulation of perivascular afferents was designed by retrograde cannulation of femoral artery, using a 24G, double ported polyethylene cannula. The vertical port of which was used to inject the algogen into the artery and horizontal port to measure the BP continuously, as this port was connected to the pressure transducer. Previously, separate carotid artery cannulation was used for the BP recording. But our experimental design excluded the need for carotid artery cannulation that might compromise the circulation to the CNS centers mediating cardiorespiratory reflex responses. After cannulation, the proximal end of femoral artery became an end artery and the drugs were instilled retrogradely. The volume of chemicals was kept minimal (100 µl) and the ipsilateral femoral vein was also ligated. These measures made sure that the instilled drug remained in a local segment of femoral artery and did not spill out to the systemic circulation. Further, there was no increase in the water content of ipsilateral paw as compared to the contralateral paw. This finding also substantiates our proposition regarding minimal systemic spillage. The femoral artery is cannulated by a double ported cannula. This cannula helps instillation of algogen and BP measurement simultaneously. Retrograde instillation helps to deposit the algogen in a local segment of femoral artery.

Ipsilateral somatic nerves mediate histamine-induced vasosensory reflex responses involving perivascular afferents in rat models

“…In the present study, histamine was instilled in a local segment of femoral artery and the changes in BP were studied along with changes in HR, RF and RMV. Further, the experimental design was modified using a 24G, double ported cannula, prepared in our laboratory 11 . This cannula helped us avoid the cannulation of carotid artery 2 , 3 , 6 , thereby minimizing the circulatory compromise to the CVR centres located in the pons and medulla.…”

“…1 . The detailed methodology of dissection and recording was standardized, validated and published in our previous articles 10 , 11 and a brief relevant description is given below.…”

“…The wet weights of paws were determined and were dried in an electric oven (90 °C) for a period of 72 h. The difference between wet weight and dry weight of a paw provided its water content and was expressed as percentage of wet weight. This methodology of paw edema estimation was standardized and described in detail in our previous publications 10 , 11 .…”

“…injection of histamine has not yet been described so far, to the best of our knowledge. Further, we have developed a novel experimental design in which the minimum and constant volume of nociceptive agonist can be deposited in a segment of an artery 11 . In the present study, histamine was used as a tool for the elicitation of vasosensory reflex responses.…”

Perivascular histamine receptors mediate vasosensory reflex responses elicited by thermal nociceptive stimuli in anaesthetised rat models

“…[2,3,13] Works from our laboratory have demonstrated similar reflex responses using histamine, bradykinin and Mesobuthus tamulus (BT) venom as nociceptive tools. [4,[14][15][16][17][18] Although vasosensory reflex responses elicited by chemical nociceptive stimuli have been studied extensively, the same is not true with thermal and mechanical nociceptive stimuli. Therefore, the present study was conducted to study the nature of vasosensory reflex responses elicited by thermal nociceptive stimuli (warm and cold) and to evaluate the role of histamine, a principal mediator of inflammation in mediating these responses.…”