The potential for prazosin and calcitonin gene-related peptide (CGRP) in causing hypoxia in tumours

Effect of Vasoactive Drugs on Tumour Blood Flow as Determined by2H Nuclear Magnetic Resonance Spectroscopy

“…Both prazosin and CGRP reduced TBF by c. 50% for an approximately 20% reduction in MABP. These results are also consistent with our earlier report of indirectly monitored changes in blood flow caused by these drugs using 31P NMR spectroscopy (9).…”

“…Hydralazine at larger doses has been shown to cause a decrease in the ratio of nucleotide triphosphates to inorganic phosphate (PNTPIP,), consistent with a reduction in TBF. However, for smaller doses, causing clinically acceptable reduction in blood pressure, it caused an increase in PNTPIPi, consistent with an increase in TBF (6,7,9). Both prazosin and CGRP reduced TBF by c. 50% for an approximately 20% reduction in MABP.…”

“…Previously, we used 31P MRS to measure nucleotide triphosphates, inorganic phosphate and intracellular pH as indirect indicators of TBF changes following the administration of the vasoactive drugs prazosin and calcitonin gene-related peptide (9). In the present study, we have…”

“…For a small, clinically acceptable, reduction in blood pressure, hydralazine has even been shown to cause an increase in TBF (8,9). In addition, hydralazine has been found to be an ineffective or unreliable modulator of TBF in primary murine tumours (10,11).…”

Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours

“…One vascular intervention currently being assessed for its ability to improve tumour oxygenation prior to radiotherapy is carbogen (95% CO 2 /5%O 2 ) breathing and nicotinamide in combination. 11 Conversely, hypotensive agents such as calcitonin gene related peptide (CGRP) 12 and hydralazine 13 have been used to further increase tumour hypoxia in order to enhance the action of bioreductive agents.…”