Biomedical subjects

F Bari

Publications and source records attributed to F Bari.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Effects of calcium channel blockers on cold-induced vasodilatation and elevated sympathetic tone in the canine internal maxillary artery bed.

This study was concerned with the interactive effects of cold-induced vasodilatation, blockade of voltage-sensitive Ca2+ channels and sympathetic nerve stimulation in the nasal vascular bed of anesthetized dogs. To estimate the distribution of the internal maxillary artery blood flow to capillaries and to arteriovenous anastomoses (AVA), the microsphere technique in combination with electromagnetic flowmetry was used. Intraarterial infusion of verapamil resulted in a dose-dependent vasodilatation and a redistribution of the internal maxillary artery blood flow. Simultaneously applied electrical stimulation of the cervical sympathetic trunk resulted in a significant fall in blood flow, caused mainly by a decrease in capillary flow. Verapamil infusion combined with cold exposure led to a simultaneous elevation of the AVA and capillary flows. When electrical stimulation of the cervical sympathetic trunk was also applied, the AVA and capillary flows were affected in different manners, depending on the sequence of the stimulations. Analysis of capillary flow data in the various nasal and facial tissue compartments indicates that cold exposure, blockade of the voltage-dependent Ca2+ channels and an elevated sympathetic tone modify the local nutritive blood flow.

Animals↗

PubMedDate not supplied

Isometric handgrip exercise-induced muscarinic vasodilation in the human skin microvasculature.

The existence of an active vasodilator system in the human skin microvasculature is well documented, but its physiological role and the underlying mechanisms are not completely understood. Cutaneous blood flow increases during isometric handgrip exercise. To examine whether this response is mediated by active vasodilation, isometric handgrip exercise testing was performed in nine healthy subjects. Local iontophoresis of atropine was applied to the forearm skin. Skin blood flow (SBF) monitoring by means of laser Doppler flowmetry was combined with continuous noninvasive blood pressure monitoring. SBF monitoring was performed at a site pretreated with atropine and an adjacent control area. Mean arterial pressure (MAP) was recorded noninvasively. Cutaneous vascular resistance (CVR) was calculated as MAP/SBF for the atropine treated and the control areas. Changes in CVR were expressed as percent deviation from the baseline (dCVR). Isometric handgrip exercise resulted in a marked reduction in CVR at the control site (dCVR: -66 +/- 4%). In contrast, the CVR was not significantly altered at the atropinetreated site (2.4 +/- 7%). It is concluded that isometric exercise induces an atropine-sensitive vasodilation which is mediated by muscarinic receptors in the human skin.

Adult↗

PubMedDate not supplied

Short-term monitoring of the vascular resistance of the human skin microvasculature.

OBJECTIVE AND METHOD: Laser Doppler flowmetry is a non-invasive tool in assessing the temporary changes of skin microcirculation. Another non-invasive equipment the Finapres 2300 finger blood pressure monitor provides a continuous blood pressure signal. The combination of the two devices allows short-term monitoring of the changes in the resistance of skin microvasculature. In order to assess the role of skin blood vessels in physiological responses to complex reflex tests Valsalva manoeuvre was performed by 12 healthy volunteers. For comparison a thermal stimulation (cold pressor) test was also done. RESULTS: The two tests resulted in skin blood flow responses of similar magnitude. The changes in calculated regional peripheral resistance (dRPR) indicated that both responses involved active vasoconstrictor mechanisms. It is of importance that the active vasoconstriction could be documented only at the late strain phase (V2) but not in the early strain phase (V1) of the Valsalva manoeuvre (%dRPR in V1 = 0.14 vs. V2 = 0.96, p < 0.05). CONCLUSIONS: In conclusion our findings support the theory that changes in the tone of the skin blood vessels parallel the changes in systemic vasculature in response to complex reflex tests. This is the first report which documents the feasibility of the continuous monitoring of the regional peripheral resistance.

Adolescent↗