Muscarinic receptor gene expression was quantified in isolated ophthalmic arteries of wild-type mice using real-time PCR. These findings provide the first evidence that M 3 receptors are critically involved in cholinergic regulation of diameter in murine ophthalmic arteries. Deletion of either M 3 or M 5 receptor did not affect responses to nonmuscarinic vasodilators such as bradykinin or nitroprusside.Ĭonclusions. Strikingly, cholinergic dilation of ophthalmic arteries was almost completely abolished in M3R −/− mice. In functional studies, after preconstriction with phenylephrine, acetylcholine and carbachol produced concentration-dependent dilations of ophthalmic arteries that were similar in M5R −/− and wild-type mice. However, mRNA levels of M 1, M 3, and M 5 receptors were higher than those of M 2 and M 4 receptors. With the use of real-time PCR, all five muscarinic receptor subtypes were detected in ophthalmic arteries. Changes in luminal vessel diameter in response to muscarinic and nonmuscarinic receptor agonists were measured by video microscopy. To test the functional relevance of M 3 and M 5 receptors, ophthalmic arteries from mice deficient in either subtype (M3R −/−, M5R −/−, respectively) and wild-type controls were isolated, cannulated with micropipettes, and pressurized. Muscarinic receptor gene expression was quantified in murine ophthalmic arteries using real-time PCR. To determine the functional role of M 3 and M 5 muscarinic acetylcholine receptor subtypes in ophthalmic arteries using gene-targeted mice. Based on these results, a modified classification of the developmental stages has been proposed.Purpose. All growth and rotation ceased about 1 h before ejection of the sporangium into the air. During this period of growth, the sporangiophore rotated in a clockwise direction as viewed from above. Elongation then recommenced in the newly established growth zone in the upper region of the sporangiophore just beneath the subsporangial vesicle. Radial expansion of the subsporangial vesicle continued at a decreasing rate until full size was reached. A transient cessation of elongation after sporangium development was followed by resumption of both elongation and radial expansion in the region beneath the sporangium developing the subsporangial vesicle. The elongation rate of the sporangiophore apex then gradually decreased and the apex expanded radially to produce the sporangium, but no rotation occurred. The sporangiophore initial emerged from the trophocyst and elongated at the extreme tip without rotating. The growth and rotation of the sporangiophore of Pilobolus crystallinus, which are important factors in its phototropic behavior, were analyzed throughout its development.
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